公共技术中心___中国科学院地质与地球物理研究所.pdf

Rough and medium vacuum The generation of rough and medium vacuum 2 MolecularVacuum Pumps Turbomolecular Vacuum Pumps Roots Vacuum Pumps Diffusion Ejector Pumps Fractionating Diffusion Pumps Self Cleaning Diffusion Pumps Diffusion Pumps Ejector Vacuum Pumps RadialVacuum Pumps Liquid Jet Vacuum Pumps Gas Jet Vacuum Pumps Rotary Piston Vacuum Pumps Centrifugal Vacuum Pumps Ion Transfer Pumps Driving Jet Vacuum Pumps Liquid Entrainment Vacuum Pumps Kinetic Vacuum Pumps Vacuum Pumps (functional principles) AxialVacuum Pumps TurboVacuum Pumps Rotary Vane Vacuum Pumps Reciprocating Vacuum Pumps Multi Cell Vacuum Pumps Gas Ring Vacuum Pumps Mechanical Kinetic Vacuum Pumps Liquid Ring Vacuum Pumps Rotary Positive Displacement Vacuum Pumps Diaphragm Vacuum Pumps Oscillation Positive Displacement Vacuum Pumps Positive Displacement Vacuum Pumps Gas Transfer Vacuum Pumps Condensers Cryo Pumps Sputtering Ion Pumps Evaporator Ion Pumps Ion Getter Pumps Sublimation Pumps Bulk Getter Pumps Getter Pumps Adsorption Pumps Gas Binding Vacuum Pumps Generation of rough and medium vacuum Chart Index ........................................................................................................................Page 1 1 Rotary Vane Vacuum Pumps 1.1 Design and Function.......................................................................... 4 1.2 Accessories ........................................................................................ 9 2 2.1 2.2 2.3 Roots Vacuum Pumps Design and Function ...................................................................... 12 Design and Function of the Circulatory Gas Cooled Roots Vacuum Pumps (WGK) ........................................................ 15 Special Equipment and Accessories .............................................. 17 3 3.1 3.2 3.3 3.4 Liquid Ring Vacuum Pumps Design and Function ...................................................................... 20 Fresh Fluid Operations .................................................................... 20 Combined Fluid Operations............................................................ 21 Closed – Circuit Fluid Operations .................................................. 21 4 4.1 4.2 Condensers Design and Function........................................................................ 22 Condenser Calculations .................................................................. 23 5 5.1 5.2 Heat Exchangers Design and Function........................................................................ 24 Heat Exchanger Calculations .......................................................... 25 6 Backing Pump Selection ................................................................ 26 7 7.1 7.2 7.2.1 7.7 7.8 7.9 Calculations Power Consumption of a Roots Vacuum Pump............................ 29 Volume Flow Rate of a Roots Vacuum Pumping Station ............ 30 Calculating the Volume Flow Rate of a WOD 220 A Pumping Station ........................................................ 31 Volumetric Efficiency Rating .......................................................... 33 Conductance Calculations .............................................................. 33 Pump Down Times .......................................................................... 36 The Influence of Leaks on Pump Down Times and End Vacuum (Leak Rate) .......................................................... 38 Drying Process ................................................................................ 39 Boyle-Mariotte Law ........................................................................ 40 Selecting a Vacuum Pumping Station .......................................... 40 8 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 Appendix Graphical Symbols in Vacuum Technology .................................. 44 Definition of terms in Vacuum Technology .................................. 46 Operating medium .......................................................................... 50 Conversion Tables .......................................................................... 51 Data on Various Substances .......................................................... 52 Desorption Rates on Clean Surfaces.............................................. 54 Correction Factor a .......................................................................... 54 Technical Data, Rotary Vane Vacuum Pumps................................ 55 Technical Data, Roots Vacuum Pumps WKP ................................ 58 Technical Data, Roots Vacuum Pumping Stations ........................ 60 9 Technical Formulas.......................................................................... 62 7.3 7.4 7.5 7.6 3 Rotary Vane Vacuum Pumps 1 Rotary Vane Vacuum Pumps Single and two-stage rotary vane vacuum pumps with volume flow rates from 2.5 m3/h to 630 m3/h, with ultimate pressures of up to < 6 ·10-3 mbar are used for all vacuum processes in the rough and medium vacuum range. They can run as stand alone units or be utilized as a backing pump for vacuum pumps which do not compress against atmosphere, such as Roots vacuum pumps or turbomolecular pumps. Fig.1: Function diagram of a rotary vane vacuum pump of singleand two-stage design (Pfeiffer Vacuum GmbH). 1 Pump cylinder, 2 Compression chamber, 3 Rotor, 4 Vane, 5 Gas ballast inlet, 6 Exhaust, 7 Valve, 8 Oil level, 9 Vacuum connection, 10 Connecting passage 1.1 Design and function The rotary vane vacuum pump is a typical example of an oil-immersed positive displacement pump. The central component of a rotary vane vacuum pump is the pumping system. It consists of a cylinder with ports leading to the outside. These ports are used to take in and exhaust the gases to be pumped. Inside the cylinder, there is an eccentrically-arranged rotor. The vanes are fitted into slots on the rotor. The vanes, which glide along the cylinder wall, divide the available inner space into working chambers. During one full rotation of the rotor, the chamber volume increases from zero to the maximum volume and then decreases continually until it reaches the minimum value. Actual pumping is effected by the increase and decrease in size of the sickleshaped chambers of the working space. 4 The decrease in chamber volume compresses the enclosed gases. The compression at approximately 200 mbar above atmospheric pressure allows for the gas pressure to be higher than the opening pressure of the exhaust valve. Rotary vane vacuum pumps are available in single and two-stage models. Two-stage pumps have a lower ultimate pressure than singlestage pumps. Rotary vane vacuum pumps can be used without problem whenever the medium to be pumped is a gas that cannot condense at the operating temperature of the pump and at atmospheric pressure. In the chemical industry, with its numerous distillation and drying processes, vapors also have to be pumped, which may condense completely or partly in the pump during the compression phase. Such condensation in the pump is always undesirable. It may speed up degradation of the operating medium or corrosion inside the pump. In addition, a deterioration of the attainable ultimate pressure must be expected when the condensate and the operating medium get mixed. Vapors with a sufficiently high vapor pressure, which do not decompose the pump oil, can be pumped with the rotary vane vacuum pump. If, however, substances are pumped which chemically attack and decompose the pump oil or have such a low vapor pressure that condensation in the pump cannot be avoided despite gas ballast, another type of backing pump should be chosen. Gas ballast Rotary vane pumps have to be equipped with a device which facilitates pumping of certain quantities of process gases in chemical vacuum applications. The most feasible solution to this is the gas ballast principle. With the gas ballast method devolved by G a e d e, a metered quantity of gas is admitted continuously into the expansion chamber of the pump. Therefore, the outlet valve is open before condensation can occur. The inlet of gas, usually atmospheric air, starts immediately after the vanes fitted into the rotor shut off the expansion chamber from the intake port. This reduces the negative effect which may cause a deterioration of the ultimate pressure. Maximum tolerable water vapor inlet pressure (to DIN 28 426 or PNEUROP) “The maximum tolerable water vapor inlet pressure is the highest water vapor pressure at which a vacuum pump, under normal ambient conditions (20°C, 1013 mbar), can pump and exhaust water vapor in continuous operation. It is given in mbar.” The maximum tolerable water vapor inlet pressure changes with: - Higher ambient temperature: the max tolerable water vapor inlet pressure rises. - Higher pump temperature: the max. tolerable water vapor inlet pressure rises. - Higher backpressure (on exhaust side): the max. tolerable water vapor inlet pressure drops. - Higher permanent gas quantity with equal water vapor quantity: the max. tolerable water vapor inlet pressure rises. - Reduced gas ballast quantity: the max. tolerable water vapor inlet pressure drops. - Increasing water vapor content in the gas ballast: the max. tolerable water vapor inlet pressure drops. Assuming a ratio of gas ballast volume to volume flow rate of 10%, this results in the max. tolerable vapor inlet pressures given in table 1 for different operating temperatures. The opening pressure of the outlet valve in this example is 1200 mbar. It can be clearly seen that the max. tolerable vapor inlet pressure depends on the operating temperature to a very high degree. High max. tolerable vapor inlet pressures can only be reached with operating pressures which are clearly above 70°C. The upper limit temperatures are determined by the oil temperature and seal materials used. 5 Rotary Vane Vacuum Pumps The effects of the gas ballast on the maximum tolerable vapor inlet pressure can be shown by the fundamental principles of thermodynamics. According to these, this pressure can be calculated as follows: B (m3/h) Gas ballast volume S (m3/h) The nominal volume flow ps (mbar) Saturation vapor pressure of the water vapor pumped at the pump’s operating temperature B 1333 (ps-pa) [mbar] pWo= –––– · ––––––––––––– S 1333 – ps (mbar) pa Water vapor partial pressure of atmospheric air (value in practical operation pa = 13 mbar) Equation 1 pv (mbar) Pressure in exhaust port of the pump Max. tolerable inlet pressures for other vapors are defined in DIN 28 426. pSD (mbar) Saturation pressure of vapour component at pump operating temperature Generally, the following equation is used for calculation: pv (pSD – pAD) pSD – pL B pD = –––– · –––––––––––––– + –––––––– [mbar] pv – pSD pv – pSD S pAD (mbar) Partial pressure of vaporized substance in atmospheric air pL (mbar) Permanent gas partial pressure at intake port Equation 2 pD (mbar) Maximum tolerable vapor inlet pressure qpv S Ratio of gas ballast inlet volume to volume flow rate of backing pump pwo (mbar) Maximum tolerable water vapor inlet pressure PNEUROP Operating temperature (° C) qpv S 50 60 70 80 90 0,1 0,1 0,1 0,1 0,1 TB (°C) Operating temperature of the pump TS (°C) Boiling temperature of the substance pumped off at the pressure in the exhaust port of the pump Max. tolerable water vapor inlet pressure (mbar) Max. tolerable styrene vapor inlet pressure (mbar) 10 18 34 63 134 3 5 7 12 18 Table 1 Medium to be pumped Temperature Condensation Result Soluble in operating medium TB > TS no Oil dilution TB < TS yes Oil dilution TB > TS no ––––– TB < TS yes Forming an emulsion Not soluble in operating medium Table 2 6 Fig. 2 Section through a two-stage rotary vane vacuum pump (Pfeiffer Vacuum GmbH). 1 Oil filling plug 2 Cap 3 Pressure relief valve 4 Pump valve 5 Support stand 6 Gas ballast valve 7 On/Off switch with motor protection switch 8 High vacuum safety valve 9 Vacuum connection 10 Exhaust connection 11 Pump valve 12 Intake channel 13 Solenoid valve 14 Vane 15 Rotor 16 Working chamber 17 Pump cylinder 18 Monitoring connection 19 Motor 20 Base plate 21 Coupling 22 D.C. generator 23 Radial shaft seal 24 Pumping stage II 25 Pumping stage I 26 Oil drain plug 27 Sight glass 28 Oil level Drive Depending on their size, the pumps are equipped with single or three-phase motors. The three-phase motors have PTC resistor temperature sensors fitted into the windings. To utilize these temperature sensors, a tripping device is required. All motors have the starting torque required by PNEUROP for cold starting at 12°C. 7 Rotary Vane Vacuum Pumps Magnetic-coupled rotary vane vacuum pumps The new drive concept - “the integrated magnetic coupling“ - is the latest innovation within the rotary vane pump market. The separation of the rotor and motor shaft eliminates the problem of the radial shaft seal providing a hermeticalled sealed pump. The wear-free drive prevents leaks (no contamination from leaking oil), minimizes maintenance and increases the MTTF (meantime to failure): providing low cost of ownership. (Figure 3) Silencer The silencer provides a quiet running pump. For this, small quantities of gas are continuously admitted to the oil circuit. The silencer has been designed so that only the pumped gas is fed into the oil circuit. This prevents any contamination of expensive or sensitive gases by atmospheric air. The silencing device is accessible from outside. If necessary, it can be readjusted while the pump is running. High-vacuum safety valve During intentional and unintentional shutdowns, an integrated high-vacuum safety valve with a leak rate of <1 · 10-5 mbar I/s immediately separates the pump from the vacuum chambers and vents the pump. The HV safety valve responds as soon as the nominal rotation speed of the pump falls below 10%. It prevents the rise of oil to the vacuum chambers and vents the pumping system with the pumped gas. It delays opening so that a pressure compensation is achieved between the pump and vacuum chambers. Depending on the pump type, the high-vacuum safety valve is controlled by either the DC generater on the solenoid valve or the oil pressure. radial shaft seal O-ring inner magnet coupling “vacuum“ “vacuum“ motor shaft rotor shaft ”environment“ motor shaft rotor shaft ”environment“ “vacuum“ “vacuum“ outer magnet sleeve Fig. 3 Traditional drive concept 8 can New, wear free drive concept with magnetic coupling Fig. 4 Accessories FAK – Activated carbon filter FBL – Clay filter KAS – Condensate separator KLF – Cold trap KWK – Crystallization cooler ONF – Oil mist filter FAK ORF – Oil return device STP – Dust separator STR – Dust separator STZ – Dust separator URB – Catalyzer trap ZFH – Heating rod ZFO – Zeolite trap ZFH ONF FBL FAK ONF KAS KAS KLF FAK STP STR STZ URB ZFO KWK BAFFLE ORF ORF Outlet Inlet UNO/ DUO 1.2 Accessories Separators Condensate separator (KAS) Condensates may form in the intake and exhaust lines of vacuum systems when vapors are pumped off. To protect the pump from such condensates, it is recommended to install a condensate separator both in the intake line and in the exhaust line. Oil mist filter (ONF) Oil mist filters are fitted to the exhaust port of rotary vane vacuum pumps. They prevent contamination of the air by oil mists which, depending on the working pressure, are exhausted by the pumps in large or small quantities. The oil mist filter consists of a cylindrical filter element of porous ceramic material and an aluminum housing, with oil container. OFC Oil return device (ORF) The ORF, in combination with the oil mist filter, collects and returns oil back into the pump. It helps to reduce the operating costs, especially when special oils are used. Dust separator (STP, STR, STZ) A dust separator is required if the process generates dust particles that can reach the pump. Crystallization cooler (KWK) This cooler is used for special processes in semiconductor production, e.g. LPCVD. It can also be used to cool hot gases and vapors to temperatures which are not detrimental to the rotary vane vacuum pump. 9 Rotary Vane Vacuum Pumps Adsorption trap Reduces backstreaming of oil. The ultimate pressure and residual gas compositions are strongly influenced by hydrocarbons streaming back from rotary vane vacuum pumps. Therefore, traps are installed on the backing pressure side of high vacuum pumps to obtain a hydrocarbon-free vacuum in the process chamber. Zeolite (ZFO) The zeolite trap prevents backstreaming of hydrocarbons from rotary vane vacuum pumps to downstream high vacuum components by adsorption. The adsorbent can be regenerated by baking out at 300°C. The regeneration intervals depend on the process. Catalyzer trap (URB) The catalyzer trap prevents backstreaming of hydrocarbons on single or two-stage rotary vane vacuum pumps by catalytic combustion. The oxygen supplied to the trap from periodic venting of the process chamber is sufficient for self cleaning of the trap. The regeneration intervals are therefore, independent of the process. Water cooling is required if the trap is fitted directly to the intake port and if it is used with single-stage rotary vane vacuum pumps. Cold trap (KLF) The cold trap prevents backstreaming of hydrocarbons from single or two-stage rotary vane vacuum pumps by condensation. The cold trap also provides effective protection for the rotary vane vacuum pump when aggressive media are pumped. It can be operated with different coolants, e.g. LN2 or CO2. The regeneration intervals and the coolant consumption depend on the process. 10 Filters Protects the rotary vane vacuum pump and the operating medium. The vapors produced by certain processes can attack the operating media and decrease the life-time of the pump. The filters available have high adsorption capacity and ara well suited for such vapor producing processes. Activated carbon filter (FAK) This filter is used if H2S, HCN, Hg, NH3, SO2 gases and solvent, acid and alkaline vapors are present. The activated carbon filters are delivered with one filling. The activated carbon filling can be exchanged. The service life of the filter filling depends on the process. Clay filter (FBL) The clay filter protects the rotary vane vacuum pump and the operating medium by adsorbing organic vapors. The clay filling can be exchanged. The service life of the filter filling depends on the process. This filter is used for peroxides, hydroperoxides and polycondensates in the petrochemical, plastics and resin chemical industries. Oil Filters Chemical oil filter (OFC) The chemical oil filter is installed within the oil flow path of rotary vane vacuum pumps. The oil filter prevents wear on the pump and increases the life of the oil by filtering out dust and particles and by absorbing corrosive substances from the pump oil. Magnetic coupled Rotary Vane Vacuum Pump Rotary Vane Vacuum Pumps DuoLine 11 Roots Vacuum Pumps 2 Roots Vacuum Pumps (WKP) Roots Vacuum Pump In principle, the Roots vacuum pump represents the ideal, dry operating vacuum pump. Roots vacuum pumps, in conjunction with backing pumps such as rotary vane vacuum pumps and gascooled Roots vacuum pumps, are used for all applications involving the rough to medium vacuum range where large volume flow rates are required. Circulatory gas cooled Roots Vacuum Pumps Circulatory gas cooled Roots vacuum pumps of the series WGK differ from the non-cooled series WKP in that they can be operated without backing pumps in the pressure range 130 to 1013 mbar. Since no backing pumps ara required, the pumped medium is not contaminated by operating fluids and pollutants are ot released into the drainage system. When combined with additional Roots vacuum pumps, a final pressure in the medium vacuum range is attainable. 2.1 Design and Function of Roots Vacuum Pumps The Roots Vacuum Pump is a positive displacement pump developed for vacuum operations. It has a high compression ratio coupled with a large volume flow rate in the pressure range 50 mbar to 1 · 10-3 mbar. The pumps work on a 100 year old Roots principle whereby two synchronous rotors turn, without contact, in a housing. 12 Pumping occurs via two figure eight shaped counter-rotating rotors synchronized by means of a pair of gears which are fitted to the ends of the rotor shafts. Pumping chambers are formed by the housing while the two rotors seal against each other without contact. The Roots vacuum pump can operate at high rotational speeds (1500-3000 rpm) because no friction takes place in the puming chamber. The lubrication is limited to the gear and bearing housings which are separated from the pumping chamber. The absence of reciprocating parts allows perfect dynamic balancing so that despite high rotational speeds the Roots vacuum pump runs very quietly. One of the outstanding features of the Roots vacuum pump is, relative to its size, the large volume flow rate. However, above certain differential pressures between intake and discharge side, thermal overloading can arise if an effective compression ratio of 1:2 is exceeded. This can lead to seizing and possible destruction of the pump. Depending on the process involved, the dry compressing Roots vacuum pump can be combined with various backing pumps, e.g. rotary vane vacuum pumps, liquid ring vacuum pumps, dry backing pumps, multi-stage Roots vacuum pumps or, for special applications, an in-line series of circulatory gas cooled Roots vacuum pumps. Fig. 5 Sectional representation of a Roots vacuum pump (WKP 500 A, Pfeiffer Vacuum GmbH). 1 Motor 2 Moveable bearing 3 Intake connection 4 Roots vacuum pump 5 Labyrinth seal 6 Gears 7 Overflow valve 8 Pumping chamber 9 Sight glass 10 Oil return line The drawing shows a longitudinal view of a Roots vacuum pump. The direction of delivery is vertical, from top to bottom, so that any particles suspended in the suction stream can be carried out of the pump. The rotor shaft bearings are fitted on both ends: On one end as a fixed bearing and on the other with a moveable inner ring to allow for the unequal expansion between the housing and rotors. The bearings are 11 Temperature control 12 Discharge connection 13 Fixed bearing lubricated by immersing gears and splash rings into oil reservoires. Labyrinth sealing system, centrifugal rings and oil return channels, fitted between bearing and pumping chamber, prevent the lubricating oil from entering into the pumping chamber. In the standard design, the extension of the drive shaft to the outside is sealed with oil lubricated radial shaft seals. The radial shaft seals run on a special bushing to protect the shaft. 13 Roots Vacuum Pumps Overflow valve The overflow valve is connected to the intake and discharge lines of the pump via conduits. A gravity type plate valve which is adjusted to the permissible pressure differential of the pump opens when the pressure differential is exceeded and allows, depending on the volume of gas, a greater or lesser part of the sucked in gas to backstream from the discharge to the intake side. This arrangement enables the Roots vacuum pump to cut in at atmospheric pressure and protect both the pump and its motor from thermal overloading. Another advantage is fast pump down times. Since the Roots vacuum pump can start at atmosphere with the backing pump, a larger volume flow rate is possible versus just having the backing pump operate by itself. S [m3/h] 104 ➁ ➂ 103 WKP 1000 A ➂ ➁ ➀ ➃ 102 UNO 120A 10 1 10–3 10–2 10–1 100 101 102 Fig. 6 1) Volume flow rate curve of the backing pump 2) Volume flow rate curve of the Roots vacuum pump (cutting in at 7 mbar) 3) Volume flow rate curve of the Roots vacuum pump with overflow valve 4) Gain in volume flow rate through 3 Vacuum Pumping Station WOD 900 A (Pfeiffer Vacuum GmbH) comprising of a WKP 1000 A and UNO 120. 14 103 p [mbar] Fig. 7 Sectional representation of a circulatory gas cooled Roots vacuum pump (WGK, Pfeiffer Vacuum GmbH). 1 Intake connection 2 Moveable bearing 3 Labyrinth seal 4 Gears 5 Sight glass 6 Cooling gas inlet 7 Rotor 8 Pumping chamber 9 Gas cooler 10 Discharge connection 2.2 Design and Function of the Circulatory Gas Cooled Roots Vacuum Pumps The circulatory gas cooled Roots vacuum pump (WGK) has been designed for extreme applications. There are no restrictions where high differential pressures and compression ratios are involved. During the compression and discharge phases, the heat is dispersed by an efficient gas 11 Temperature control 12 Oil return line 13 Fixed bearing circulation system. This means that this version can be operated under conditions where the conventional Roots vacuum pump can not be used. Due to their design the rotors are able to control the tronsport of the rocess gas and of the cooling gas. The pump cannot overheat, even during final pressure operations with closed intake line. 15 Roots Vacuum Pumps Cooling gas connection Cooling gas connections are located on the sides of the pump. The design of the rotors prevent cooling gas from backstreaming to the intake side. Therefore, the volume flow rate is not affected. Heat exchanger and motors (for circulatory gas cooled Roots vacuum pumps) A heat exchanger and motor are required to operate the gas cooled pump. The size and type is determined by the application. 5 3 p1 5 3 4 4 4 4 p1 4 p1 4 4 2 6 2 1 6 7 p2 Phase III 5 3 4 1 7 p2 Phase II 5 3 2 1 6 7 p2 Phase I p1 4 2 1 6 7 5 3 4 2 1 p1 WKP and WGK drives Motor and pump shafts are connected by an coupling. The motor side shaft feedthrough is fitted with radial shaft sears having a replaceable protective bushing. The space between the sealing rings is filled with sealing oil via an oiler. The sealing oil should be the pump operating medium. 6 7 p2 Phase IV p2 Phase V Fig. 8 Principle of the circulatory gas cooled Roots vacuum pumps (WGK, Pfeiffer Vacuum GmbH). PHASE I Space 3 is connected to intake port 5 and sucks in gas at a pressure of p1 when rotors 1 and 2 turn. PHASE II Space 3 is sealed off from both intake port 5 and from cold gas inlet 4. PHASE III Cold gas streams into space 3 via the cold gas circulation until counter pressure p2 is attained. 16 PHASE IV Space 3 is closed to both cold gas inlet 4 and discharge port 6. PHASE V Space 3 is connected to discharge port 6 and the sucked- in gas mixture from intake port 5 and cold gas inlet 4 is expelled. Behind cooler 7 some of the gas, representing the gas volume sucked in at intake port 5, streams into the next pump in series (or is released). 2.3 Special Equipment and Accessories Fig. 9 Section through a Roots Vacuum Pump. (WKP 500 A, Pfeiffer Vacuum GmbH). 1 Gear wheels 2 Splash disc 3 O-ring seal 4 Rotors 5 Overflow valve 6 Connection for gear chamber evacuation 7 Oiler 8 Radial shaft seals 9 Motor 10 Coupling 11 Roller bearing 12 Measuring connection 13 Self-aligning ball bearing 14 Sealing gas connection 17 Roots Vacuum Pumps Measuring connections The measuring connections on the intake and discharge side of the pump can be utilized to monitor temperature and pressure. The locking screws can be replaced with ISO-KF screw-on small flanges to enable transducers to be connected. Sealing gas connection When pumping solvents and reactive gases that life-time of the the lubricant can decrease due to condensation. Reactive gases and vapors can also attack parts of the gear chamber. To prevent this, sealing gas can be introduced into the radial shaft feedthrough area between the working and gear chambers. An inert gas is used as the sealing gas, such as nitrogen (N2). 18 Surface protection Corrosive gases are present in certain applications. Pump parts which come into contact with such media can be provided with a special surface protection. The following surface treatments are possible depending on the media: -Nickel platingA nickel layer is applied to all internal parts that come in contact with the gases. -PhosphatizationFor short term surface protection, e.g. during storage or transport the working chamber of the pump is phosphatized, vented with nitrogen and sealed vacuum tight. Gear chamber evacuation For rapid evacuation utilizing large Roots Pumping Stations, it is recommended to pre-evacuate, via an oil separator, the gear chamber of a Roots vacuum pump with a separate vacuum pump. Seals Roots vacuum pumps are fitted with Viton O-rings as standard. For special applications pumps can be fitted with O-rings and sealing materials tailored to the application. Canned motor The rotor of the motor operates in vacuum, with the canned motor design. A thin walled, non-magnetic pipe between the rotor and the stator of the motor forms the seal against atmosphere. The advantage of the canned motor is no wear and tear on the radial shaft feedthrough (e.g. radial shaft seals). It is only recommended for clean operations because its protection class is no higher than IP 22 and cannot be designed “explosion proof”. for example – VITON/ PTFE-coated – EPDM – KALREZ Roots Vacuum Pump WKP 500 A PackageLine Roots Vacuum Pumping Station 19 Liquid Ring Vacuum Pumps 3 Liquid Ring Vacuum Pumps In principle, this pump is a combination of an “isotherm” compressing vacuum pump and a contact condenser. Compression generated heat is largely carried away by the operating fluid. Corrosive gases and vapors which condense in liquid ring pumps can be pumped without any problem when utilizing materials such as stainless steel. 1 2 6 3 4 5 ting fluid of the pump can be matched to the medium being pumped. The combination of Roots vacuum pump, gas jet and liquid ring vacuum pump attains a final pressure of approx. 0.2 mbar. If lower pressures are required, an additional Roots vacuum pump will be necessary. The running wheel is seated eccentrically in the housing. When the running wheel turns, the operating fluid in the housing forms a circulating liquid ring which rises up from the hub of the wheel. The pumped gas enters the resulting vacuum through the intake aperture. After almost one whole revolution, the liquid ring approaches the wheel hub and pushes the pumping gas out through the pressure aperture. 3.2 Fresh Fluid Operations In this type of operation, fresh operating fluid is constantly being supplied to generate the liquid ring. The temperature of the liquid ring and the operating fluid being supplied is the same. Ideally, operating fluids used in fresh fluid operations should not harm the environment. Fig. 10 Section of a single stage liquid ring vacuum pump (Siemens) 1 Rotor 2 Rotor shaft 3 Housing 4 Intake channel 5 Liquid ring 6 Flexible outlet channel 20 3.1 Design and Function Compared to rotary vane vacuum pumps, the liquid ring vacuum pump has the disadvantage of a relatively poor final pressure. This is determined by the vapor pressure of the operating fluid which is usually water. At an operational water temperature of 15°C, the liquid ring vacuum pump attains a final pressure of approx. 20 mbar. A liquid ring vacuum pump, operating cavitation free as a result of the introduction of air will attain approx. 25-30 mbar. The great advantage of the liquid ring vacuum pump is the fact that the opera- 3.3 Combined Fluid Operations In this type of operation, the “new” operating fluid in the liquid ring vacuum pump is continuously being mixed with the operating fluid discharged from the separator. The residual fluid from the separator is disposed of. 2 1 3 4 5 TA – TB KB = FB –––––––––– TA – TF 1 “Fresh“ operating fluid 2 Gas “ON“ 3 Liquid ring vacuum pump 4 Gas “OFF“ 5 Separator 6 „Used“ operating fluid 6 Fig. 11 Fresh fluid operations Equation 3 2 KB (m3/h) Fresh fluid requirements in combined operations 3 4 FB (m3/h) Operating fluid flow TA (°C) Temperature of the returned “circulating” operating fluid = discharge temperature at pump outlet port 1 TB (°C) Temperature of the operating fluid TF (°C) Temperature of the fresh fluid 1 Mixed operating fluid 2 Gas “ON“ 3 Liquid ring vacuum pump 4 Gas “OFF“ 5 Separator 6 Condensate discharge 7 “Used“ operating fluid 8 “Fresh“ operating fluid 5 6 7 8 Fig. 12 Combined fluid operations 2 3.4 Closed – Circuit Fluid Operations In this type of operation, used operating fluid, in a closed circuit, is cooled continuously via a heat exchanger. From time to time, operating fluid lost to evaporation must be replaced. 4 3 5 1 Closed – circuit fluid type of operation is used especially where the pumping of hazardous or environmentally damaging gases is involved. 7 6 9 8 10 Fig. 13 Closed-circuit fluid operations 1 Operating fluid 2 Gas “ON“ 3 Liquid ring vacuum pump 4 Gas “OFF“ 5 Separator 6 Condensate discharge 7 Heat exchanger 8 Cooling Water “OFF“ 9 Cooling Water “ON“ 10 Operating fluid supplement 21 Condensers 4 Condensers 4.1 Design and Function In many vacuum processes, e.g. drying and distillation, vapors are generated in such volumes that the water vapor capacity of the rotary vane vacuum pump is exceeded. In these cases, a condenser can provide effective protection for the pump. In addition the volume flow rate of the condenser is very high for vapors so pumping/drying times are considerably reduced. Vapor released during the process condenses on the cooling coils used to conduct the cooling medium. The resulting liquid condensate in the condensate chamber is then routed to the condensate collection reservoir via piping. S (m3/h) Volume flow rate of a vacuum pumping station ( ) mbar · m3 –––––––––– kmol · K Universal gas constant R = 83.14 R (K) TGas Gas inlet temperature p (mbar) Pressure · Q (kg/h) Material component throughput per hour M (kg/kmol) Molar mass A (m2) Cooling surface · Qw () ( ) kJ –– – h Condensation heat/volume per hour kJ –––––––––– h · m2 · K Heat exchange coefficient k (K) Tm Mean temperature difference · QH2O () kg– –– h Water vapor volume to be condensed per hour kJ ––– qH2O kg Vaporizing heat () (K) TW in Cooling water inlet temperature 1 Collecting vessel 2 Condensation chamber 3 Cooling coil 4 Shut off valve 5 Ventilation 6 Sight glass 7 Outlet valve 22 (K) TW out Cooling water outlet temperature (K) ∆Thigh Highest temperature difference (K) ∆Tsmall Smallest temperature difference Fig. 14 Condensator (KS, Pfeiffer Vacuum GmbH) TS (K) Boiling point at condensation pressure (in example 1, page 23, TS = TS H2O) 4.2 Condenser Calculations Example 1: a) Calculating the required volume flow rate of a pumping station: · · · TGas Q1 Q2 Qn S = R · –––– · –– + ––– + ··· ––– [m3/h] Mn p M1 M2   Equation 4  313 100 10 S = 83.14 · –––– · –––– + ––– 100 18 29  [m3/h] Water/vapor volume to be condensed · QH2O = 100 kg/h Inert gas part (air) in water vapor · QL = 10 kg/h Gas inlet temperature TGAS = 40 °C Cooling water temperature TW in = 25 °C Cooling water temperature TW out = 35 °C S = 1535 m3/h Working pressure pA = 100 mbar b) Calculating the cooling surface of a condenser: Molar mass of water M1 = 18 kg/kmol QW A = ––––– [m2] k·T Note! If TS is smaller than TW in or TW out no condensation is possible. Molar mass of air M2 = 29 kg/kmol m Equation 5   kJ QW = QH2O · qH2O –– h Equation 6 ∆Thigh + ∆Tsmall Tm = ––––––––––––––– [k] 2 Equation 7 ∆Thigh = Ts – TW in ∆Tsmall = Ts – TW out W kJ k ~ 1000 –––– = 3600 –––––––– m2 K h · m2 K ∆Thigh = 318 – 298 = 20 K ∆Tsmall = 318 – 308 = 10 K 20 + 10 Tm = ––––––– = 15 K 2 · Q W = 100 · 2257 = 225700 kJ/h 225700 A = ––––––––– ~ 4.5 m2 3600 · 15 is the required cooling surface of the condenser Fig. 15 Layout of a Roots vacuum pumping station (Pfeiffer Vacuum GmbH). 1 Pre-condenser 2 Condensate 2 collecting vessel 3 Venting valve 4 Float switch 5 Drain valve 6 Shut off valve 7 Roots vacuum pump 8 Overflow valve 9 Intermediate condenser 10 Rotary vane vacuum pump 11 High vacuum safety valve 12 Oil mist filter 13 Drain screw 23 Heat Exchangers 5 Heat Exchangers 5.1 Design and Function A heat exchanger is a container in which a thin partition separates two media exchanging heat without mixing. One medium flows through the space between tube and tube cladding and the other medium flows through the tube itself. The flow through the cladded space is obstructed by diversion plates setup according to the application in order to maximize the degree of cross flow to the tubes. The flow through the tubes is single or multi type depending on function, velocity and pressure loss. Heat exchangers can be used in multistage Roots vacuum pumping stations for intermediate cooling and also in gas cooled Roots vacuum pumps. In gas circulatory cooled Roots vacuum pumps the heat exchanger is fitted directly to the gas discharge port, whereby a part of the cooled gas is routed back into the pump as cooling gas. The use of the heat exchangers is based on the compression of the pumped gases (from p1 to p2) and the resultant increase in temperature (from T1 to T2). With the help of this equipment, pumps and pumping stations are protected against thermal overloading which could otherwise lead to breakdowns. Types of heat exchangers: ● Tubular: for all applications (Guide-line) 3 kW motor power of the pump for 1m2 heat exchange surface of the cooler. ● Finned: only for clean gases (Guide-line) 1 kW motor power of the pump for 1m2 heat exchange surface of the cooler. Selection of material The inner tubes of a tubular heat exchanger have the most important function. First, they form the heat exchange surface. Second, the walls of the tubes act to separate the two media. The selection of material for the inner tubes requires careful consideration because if the wall should break, the two media will mix and the heat exchanger will break down. A (m2) Exchange surface · Q ––kJh– Amount of heat to be exchanged per hour P (kW) Calculated required motor power (K) Tm Mean temperature difference between gas and cooling medium TG in (K) Gas inlet temperature TG out (K) Gas outlet temperature TW in (K) Cooling water inlet temperature TW out (K) Cooling water outlet temperature 24 5.2 Heat Exchanger Calculations The motor power for a particular working range of a circulatory gas cooled Roots vacuum pump (WGK) has been calculated to be P = 15 kW. Because the calculated motor power is the basis for establishing the amount of heat which has to be conducted away from the circulatory gas cooled Roots vacuum pump, such heat must be dispersed by the heat exchanger to prevent overheating. 1 W = 1 J/s 1 kW = 3600 kJ/h (TG in – TW out) – (TG out – TW in) [K] ∆ Tm = –––––––––––––––––––––––––––– TG in – TW out In –––––––––––– TG out – TW in ( ) Equation 8 · Q = 15 · 3600 = 54.000 kJ/h Example 2 Motor power P = 15 kW Gas inlet temperature TG in = 120 °C = 393 K Gas outlet temperature TG out = 50 °C = 323 K (assumed) Cooling water inlet temperature TW in = 30 °C = 303 K Cooling water inlet temperature TW out = 40 °C = 313 K (assumed) (393 – 313) – (323 – 303) ∆Tm = ––––––––––––––––––––––– ~ 43 K 393 – 313 In –––––––––– 323 – 303 for finned coolers where k ~ 50: ( ) 54.000 AL = ––––––– ~ 25 m2 exchange surface 50 · 43 for tubular coolers where k ~ 180: 54.000 AR = –––––––– ~ 7 m2 exchange surface 180 · 43 k ~ 50 for finned coolers k ~ 180 for tubular coolers k-values for the pressure range from atmosphere to approx. 50 mbar. · Q A = –––––– [m2] k · Tm · Q = P · 3600 [kJ/h] 25 Backing Pump Selection 6 Backing Pump Selection Rotary Vane Vacuum Pumps The rotary vane vacuum pump represents the ideal backing pump for Roots vacuum pumping stations. It has consistant pumping speed over a wide pressure range. The single stage rotary vane vacuum pump can compress from approximately 0.5 mbar to 1000 mbar even with an open gas ballast valve. This means that with this backing pump, a Roots vacuum pumping station can attain a final pressure of 10-2 mbar and lower with open gas ballast valve. Water vapor, various solvents and other vapors e.g. alcohols, paraffin and many others can be pumped by the rotary vane vacuum pump providing they have a sufficiently high vapor pressure and do not chemically decompose the pump oil. Liquid ring vacuum pumps Situations arise where substances have to be pumped which attack and decompose the backing pump oil or which have such a low vapor pressure that condensation in the pump is unavoidable. In such cases, the liquid ring vacuum pump represents a viable alternative as a backing pump. Compared to rotary vane vacuum pumps, the liquid ring vacuum pump has the disadvantage of a relatively poor final pressure. At an operational temperature of 15°C, the liquid ring vacuum pump attains a final pressure of approx. 20 mbar. A liquid ring vacuum pump, operating cavitation free as result of the introduction of air will attain 25-30 mbar at best. A combination of Roots vacuum pump and liquid ring vacuum pump will attain a final pressure of approx. 1 mbar. 26 Liquid ring vacuum pumps with gas jet The combination of Roots vacuum pump, gas jet and liquid ring vacuum pump attains a final pressure of approx. 0.2 mbar. If lower pressures are required, an additional Roots vacuum pump will be necessary. When pumping environmentally hazardous substances, liquid ring vacuum pumps must not be operated with fresh water. A closed circuit must be provided in which an appropriate operating fluid is used to remove the heat of compression via a heat exchanger. Circulatory gas cooled Roots vacuum pumps The circulatory gas cooled version of the Roots vacuum pump is another type of backing pump used for situations where high pressure differentials are involved. Because the Roots is a completely dry operating vacuum pump, it can be recommended for those situations where liquid compressing working chamber pumps are excluded. Specific applications include: - Pumping off and compressing helium on cryostats - Pumping off and compressing SF6 - Clean reclamation of diverse gases in technological processes, e.g. distillation, pumping off of molecular sieves etc. - Pumping toxic substances in closed systems - Pumping down very large vessels Figure 16 shows the number of stages required for a particular working pressure. The values are valid for air and most gases and vapors. Additional stages are necessary if the pumping of helium and hydrogen is involved. Such a pumping station configuration primarily evacuates large volumes. Figure 17 shows the volume flow rate of such a pumping station. Stage V IV III II Final pressure < 10 mbar 2·10 mbar 1 mbar -3 Workingpressure -2 ➞ ➞ ➞ 5·10-3 mbar 5·10-2 mbar 2 mbar WKP WKP WGK I 20-30 mbar 100-200 mbar ➞ ➞ 1000 mbar 30-50 mbar 300 mbar WGK WGK (WKP) Fig. 16 Relationship between attainable final pressure/working pressure and number of stages when evacuating with Roots vacuum pumps (for air). S [m3/h] Roots vacuum pumping stations with circulatory gas cooled Roots vacuum pumps present very different pumping characteristics. In extreme cases, an almost constant volume flow rate is attainable over the whole pressure range from 1 bar to 10-3 mbar. Naturally, the Roots vacuum pumps must be provided with correct motors and with outlet valves to atmosphere instead of overflow valves. 105 4 104 3 2 103 1 102 10-1 100 101 102 103 p [mbar] Fig. 17 Volume flow rate curve of a four stage Roots vacuum pumping station 1 WGK 1500 2 WGK 4000 – WGK 1500 3 WGK 8000 – WGK 4000 – WGK 1500 4 WGK 18000 – WGK 8000 – WGK 4000 – WGK 1500 27 Backing Pump Selection The diagram shows that when compressing against atmosphere, the Roots vacuum pump has a low compression rate. It then increases steadily until at a back pressure of approx. 2 mbar the maximum value of 50 to 70 is reached. The drop which then follows is based on the clearance between rotors and housing owning to the effect of backstreaming in the molecular flow range. There are limits of compression with Roots vacuum pumps in certain pressure ranges. Because of this a backing pump is required. Km Maximum compression ratio Pumped off gases and vapors stream back through the gap between rotors and pump housing in the direction of the intake side. This backstreaming reduces the effective volume flow rate of the Roots vacuum pump and becomes more difficult the higher the back pressure and the greater the difference between intake and back pressure. The maximum compression ratio Km is attained if all the pumped gas has backstreamed so that the volume flow rate is zero. The Km value reflects the level of efficiency of the Roots vacuum pump and is required for the effective volume flow rate calculation. In practice, the Km value is measured at the blank flanged intake port for the required back pressure. Fig. 18 shows the compression ratio dependent on the backing pressure of the WKP series. 102 WKP 1000 A/AD, WKP 4000 A/AD, WKP 6000 A/AD WKP 2000 A/AD WKP 8000, WLP 12000 WKP 18000, WKP 25000 WKP 250 A, WKP 500A 30 101 10-2 10-1 100 Fig. 18 Maxium compression ratio Km1) for Roots vacuum pumps (WKP) when pumping air2). 28 101 102 p [mbar] 1) This Km–value is valid for pumps which operate at nominal rotational speed. 2) For helium, the value should be multiplied by a factor of 0.66. Calculations 7 Calculations Km 102 WGK 4000, WGK 8000 WGK 1500 101 WGK 500 102 101 100 103 p [mbar] Fig. 19 Maximum compression ratio Km1) for circulatory gas cooled Roots vacuum pumps (WKP) when pumping air2). 1) This Km–value is valid for pumps which operate with low nominal rotational speed. 2) For helium, the value should be multiplied by a factor of 0.66. 7.1 Power Consumption of a Roots Vacuum Pump The Roots vacuum pump is a pure positive displacement pump without internal pre-compression. For this reason, the pressure differential between intake and discharge sides and the theoretic working volume are all proportional. Sth · ∆p P = –––––––––––– [kW] 36000 ·  mech Equation 9 Sth (m3/h) Theoretical volume flow rate of Roots vacuum pumps ∆p (mbar) Pressure differential between intake and discharge ports ηmech Mechanical efficiency rate of the pump (η ~ 0.85 for Roots vacuum pumps) P (kW) Power requirements/motor power The mechanical loss is small and depending on the type of drive ranges between 5% and 15%. The use of relays for hard starting are recommended in the switch box. The power requirements after running up in the medium vacuum range are low. Example 3 A WKP 8000 Roots vacuum pump should compress gas from 0.5 mbar to 5 mbar. (Sth = 8000 m3/h). The drive power P is requred in kW. Theoretic Roots vacuum pump volume flow rate Sth = 8000 m3/h Pressure differential between intake and pressure ports ∆ p = 4.5 mbar Pump efficiency rate ηmech = 0.85 Solution: 8000 · 4.5 P = –––––––––––– = 1.18 kW drive power 36000 · 0.85 29 Calculations 7.2 Volume Flow Rate of a Roots Vacuum Pumping Station The volume flow rate of a Roots vacuum pump is dependent on back pressure in the whole suction range and is therefore influenced by the volume flow rate of the backing pump. When a Roots vacuum pump is combined with various backing pumps, different volume flow rate curves are obtained over the whole pressure range for the same Roots vacuum pump. This means that the effective volume flow rate of a Roots vacuum pump can only be stated in relation to a specific backing pump. For this reason the identification size of a Roots vacuum pump is stated in terms of the theoretical volume flow rate (also known as the nominal volume flow rate). pv (mbar) Fore-vacuum (back pressure) p (mbar) Intake pressure of the Roots vacuum pump ∆p (mbar) Set pressure differential at the overflow valve of the Roots vacuum pump Km Maximum compression ratio of the Roots vacuum pump at pv a Correction factor a (see page 54 Figure 26) ηvol Volumetric efficiency rating If it is required to compress from a specific intake pressure against a constant back pressure (e.g. condensation pressure in a condenser), an approximation of the volume flow is calculated as follows: With respect to a defined backing pump, on approximation of the volume flow is calculated as follows: Km S = Sth · ––––––––––––––– [m3/h] Sv 1.5 Sth Km +––– – ––– Sv Sth ( ) p a S = Sth · 1 – –––v · ––– [m3/h] p Km ( ) Equation 12 Equation 10 and the assigned intake pressure to: PV –––  2.5 → a = 1 p Sv · pv p = –––––– [mbar] S Equation 11 S (m3/h) Volume flow rate of the Roots vacuum pump at the intake port Sth (m3/h) Theoretical volume flow rate of the Roots vacuum pump (m3/h) Sv Volume flow rate of the backing pump at a pressure of pv 30 pV pv3 – p3 –––  2.5 → a =–––––––––– [mbar] p 0.963 · pv3 Equation 13 The volume flow rate can only be calculated according to equations 10 or 12 providing the overflow valve of the Roots vacuum pump is closed. That is, pv-p is smaller than the pressure differential set at the Km-value according to Fig. 18 for pv = 20 mbar → Km = 34 overflow valve. In the response range of the overflow valve, the volume flow rate can be calculated according to: pv · a [m3/h] S = Sth · 1 – –––––– p · Km ( Sv · (p + ∆p) S = –––––––––––– [m3/h] p ) p For –––v = 4 derived from equation 12 p →a=1 Equation 14 In this equation, ∆ p denotes the set pressure differential at the Roots vacuum pump overflow valve. In case of doubt, the calculation must be worked via the Km value (equation 10 or 12) and the overflow valve (equation 14) where the lower of the values produced is the right one. ( ) 7.2.1 Calculating the Volume Flow Rate of a WOD 220 A Pumping Station The WOD 220 A comprises a single stage rotary vane vacuum pump UNO 30 A and a Roots vacuum pump WKP 250 A. Example 5 (please also refer to Figure 20) Calculation of the pressure range of a closed overflow valve on the Roots vacuum pump (as per equations 10 and 11). Example 4 A Roots vacuum pump WKP 4000 (Sth= 4000 m3/h) should compress from 5 mbar to 20 mbar. Required is the volume flow rate. Volume flow rate [m3/h] 20 · 1 S = 4000 · 1 – –––––– = 3529 m3/h 5 · 34 at 5 mbar. 104 103 S5/p5 10 S3/p3 S4/p4 S2/p2 S1/p1 S6/p6 2 S∆6 S∆5 S∆4 S∆3 S∆2 S∆1 S7/p7 10 Sv3/pv3 Sv2/pv2 Sv1/pv1 100 101 102 Sv4/pv4 Sv5/pv5 Sv6/pv6 1 S8/p8 100 10-5 (Sv8/pv8) 10-4 10-3 Sv7/pv7 10-2 10-1 103 Intake pressure p [mbar] Fig. 20: Volume flow rate curve for example 5 31 Calculations Sv1 = 34 m3/h pv1 = 100 mbar ( (volume flow rate Sv1 at a backing pump pressure of Pv1) 12 S1 = 270 –––––––––––––––––––– = 163 m3/h 270 34 1,5 12 + –––––– – –––– 34 270 ( ) 34 · 100 p1 = ––––––––– = 21 mbar 163 33 S2 = 270 ––––––––––––––––––––1.5= 218 m3/h 270 34 33 + –––––– – –––– 34 270 ) 34 · 10 p2 = ––––––––– = 1.5 mbar 218 Sv7 = 1.0 m3/h pv7 = 0.012 mbar 1.0 · 0.012 p7 = ––––––––––– = 0.00044 mbar 27 = 4.4 · 10-4 mbar Sv8 = 0.1 m3/h pv8 = 0.01 mbar ( 47 S3 = 270 ––––––––––––––––––––1.5= 277 m3/h 270 30 47 + –––––– – –––– 30 270 ( ) 30 · 0.75 p3 = ––––––––– = 0.1 mbar 227 = 1.0 x 10-1 mbar Sv4 = 20 m3/h pv4 = 0.1 mbar 38 S4 = 270 ––––––––––––––––––––1.5= 199 m3/h 270 20 38 + –––––– – –––– 20 270 ( ) 20 · 0.1 p4 = ––––––––– = 0.01 mbar 199 = 1.0 · 10-2 mbar Sv5 = 12 m3/h pv5 = 0.04 mbar 30 S5 = 270 ––––––––––––––––––––1.5= 154 m3/h 270 12 30 + –––––– – –––– 12 270 ( ) 30 S8 = 270 ––––––––––––––––––––1.5= 3 m3/h 270 0.1 30 + –––––– – –––– 0.1 270 Sv3 = 30 m3/h pv3 = 0.75 mbar ) 12 · 0.04 p5 = ––––––––– = 0.0031 mbar 154 = 3.1 · 10-3 mbar 32 5 · 0.02 p6 = ––––––––– = 0.001 mbar 96 = 1 · 10-3 mbar ( ( ) 30 S7 = 270 ––––––––––––––––––––1.5= 27 m3/h 270 1.0 30 + –––––– – –––– 1.0 270 Sv2 = 34 m3/h pv2 = 10 mbar Sv6 = 5 m3/h pv6 = 0.02 mbar 30 S6 = 270 ––––––––––––––––––––1.5= 96 m3/h 270 12 30 + –––––– – –––– 5 270 ) 0.1 · 0.01 p8 = ––––––––– = 0.00033 mbar 3 = 3.3 · 10-4 mbar Calculation for the (pressure) range of an open overflow valve on the Roots vacuum pump (as per equation 14). 34 (1000 + 53) S∆1 = ––––––––––––––– = 36 m3/h 1000 at 1000 mbar 34 (300 + 53) S∆2 = ––––––––––––––– = 40 m3/h 300 at 300 mbar 34 (100 + 53) S∆3 = ––––––––––––––– = 52 m3/h 100 at 100 mbar 34 (30 + 53) S∆4 = ––––––––––––– = 94 m3/h 30 at 30 mbar 34 (20 + 53) S∆5 = ––––––––––––– = 124 m3/h 20 at 20 mbar 34 (7 + 53) S∆6 = ––––––––––––– = 291 m3/h 7 at 7 mbar 7.3 Volumetric Efficiency Rating The volumetric efficiency rating ηvol is often used when calculating the volume flow rate: S ηvol = ––––– Sth Equation 15 Km ηvol = –––––––––––––––– y Sv . 1.5 Sth Km + ––– – ––– Sv Sth   Equation 16 pv · a ηvol = 1– ––––––– p · Km The volume flow rate of a Roots vacuum pump is directly influenced by the volume flow rate of the backing pump. A whole range of options is available. When performing Roots vacuum pump calculations it has to be remembered that the volumetric efficiency rating falls rapidly with increasing intake pressure. If a volumetric efficiency rating of 0.85 is attained at a theoretical graduation of 10:1 to 10-1 mbar, at 4 mbar the rating has reduced to 0.7. This means that the pump is no longer effective in non-stop operations whereas in critical cases, at 10-1 a theoretical graduation of 20:1 is still viable. Between 10 and 100 mbar a graduation between 5:1 and 2:1 is possible. 7.4 Conductance Calculations The volume flow rate of a vacuum pumping station is reduced by piping and components such as valves and bellows fitted upstream of the recipient. The longer the piping and the smaller the diameter the greater the losses. The conductance value L is used to determine the extent of line losses. The value is dependent not only on the length and diameter of the piping, but also on the type of flow and the nature of the substance2) being pumped. In vacuum technology, it is laminar and molecular flow which are mainly involved. In the laminar flow range the conductance value is pressure dependent; in the molecular flow range, conductance value is pressure independent. Please note: data on substances can be found in Appendix Section 8.5, page 52 2) Conductance for round pipes is calculated universally for all pressure ranges in vacuum technology and for all types of gas: L (m3/h) Conductance value S (m3/h) Volume flow rate at the beginning of the pipe (pump) Seff (m3/h) Volume flow rate at the end of pipe (recipient) p (mbar) Pressure at the beginning of the pipe peff (mbar) Pressure at the end of the pipe pm (mbar) p + peff Mean pressure = ––––––– 2 r (cm) Pipe radius l (cm) Pipe length T (K) Gas temperature kg –––––– k mol Gas molar mass M η (Pa · s) Gas viscosity 33 Calculations —––––– 3.6 · r3 r · pm L = ––––– · (0.039 –––––– + 30 l η [m3/h] √ M––T ) For sequential arrangement of individual conductance values, the following is valid: 1 L = ––––––––––– [m3/h] 1 1 1 –– + –– + –– L1 L2 L3 Equation 17 or for air at 20 °C: Equation 21 3.6 · r3 L = –––––– (2150 · r · pm + 95) [m3/h] l For parallel arrangement of individual conductance values, the following is valid: L = L1 + L2 + L3...[m3/h] Equation 18 Laminar flow range In the laminar flow range (Figure 21) the second term in parentheses can be omitted, yielding a simplified formula for air: r4 · pm L = 7750 ––––––– [m3/h] l Equation 22 Effective volume flow rate Effective pressure The effective volume flow rate Seff at the end of the pipe is calculated from the conductance value L and the volume flow rate at the beginning of the pipe as Equation 19 1 L·S Seff = –––––– = ––––– [m3/h] 1 1 L+S –– + –– L S Air, laminary, at 20°C Molecular flow range In the molecular flow (Figure 21) the second term in parentheses can be omitted, yielding a simplified formula for air: Equation 23 and S·p peff = ––––– [mbar] Seff r3 L = 340 ––– [m3/h] l Equation 20 Air, molecular, at 20°C 34 Equation 24 d [ cm ] 100 laminar transition range 10 Fig. 21 Representation of pressure/pipe diameter dependent flow range molecular 1 10-5 10-4 10-3 10-2 10-1 100 Example 6 A pumping station connected to a non stop operating drier will attain a pressure of 0.15 mbar due to the gas volume at the pumping port. The volume flow rate is 3500m3/h. The piping has a diameter of 200 mm and is 10 m long with three 90° bends and includes an angle valve. 101 102 103 p [ mbar ] Total conductance value: 3.6 · 103 L = –––––––– · (2150 · 10 · 0.17 + 95) 1265 L = 10670 m3/h 3500 · 10670 Seff = ––––––––––––– = 2635 m3/h 3500 + 10670 The effective volume flow rate and the pressure at the drier are required. 3500 · 0.15 peff = ––––––––––––– = 0.199 ~ 0.2 mbar 2635 The equivalent pipe length as per table 3: For one pipe bend DN 200  0.6 m and for an angle valve DN 200  0.85 m. 0.2 + 0.15 pm = ––––––––––––– = 0.175 mbar 2 Total length to be used = 10 + 3 · 0.6 + 0.85 = 12.65 m Because the mean pressure is derived from the result, it must first be estimated and a value of 0.17 is taken. The actual mean pressure is 0.175 which hardly affects the final result, as can be seen. 3.6 · 103 L = –––––––– · (2150 · 10 · 0.175 + 95) 1265 L = 10978 m3/h 3500 · 10978 Seff = ––––––––––––– = 2655 m3/h 3500 + 10978 3500 · 0.15 peff = ––––––––––––– = 0.198 ~ 0.2 mbar 2655 Nominal width (mm) 10 25 40 63 100 160 200 250 350 500 1000 0.12 0.25 0.35 0.35 0.6 1.10 1.35 – – – – Angle valve 0.1 0.2 0.25 0.3 0.35 0.60 0.85 1.0 1.2 1.6 2.9 Elbow 90°, D = 3d 0.03 0.07 0.12 0.2 0.3 0.5 0.6 0.75 1.0 1.4 2.8 Y valve Table 3 Equivalent pipe lengths in m for various vacuum components 35 Calculations Example 7 At the end of a pipe with the same configurations as in the previous example, an effective volume flow rate of 2900 m3/h should be attained at 0.2 mbar for air. vacuum system, the dimensions of the exhaust lines, any vaporization of fluids, degassing of materials such as porous and large surface objects and contaminated walls. For what volume flow rate S and what intake pressure p should the pumping station be configured? If the volume flow rate S for the pressure range p1 to be calculated is constant, the pump down time can be expressed as: The length of the pipe has already been established as 12.65 m. Because the anticipated intake pressure is slightly under 0.15 mbar, the mean intake pressure is estimated as 0.17 mbar. This again yields a conductance value of: L = 10670 m3/h Equation 25 By transposing Example 8 A recipient of 12 m3 should be evacuated from 1000 mbar (atmospheric pressure) to 15 mbar in 0.3 h. What is the required volume flow rate? S·L L · Seff Seff = ––––– → S = ––––––– S+L L – Seff 10670 · 2900 S = ––––––––––––– = 3982 m3/h 10670 – 2900 and from S·p peff = –––––– Seff Seff · peff p = –––––––– S 2900 · 0.2 p = –––––––––– = 0.146 mbar 3982 0.2 + 0.146 pm = ––––––––––– = 0.173 mbar 2 Owing to the minimal deviation from the applied value (0.17 mbar), a correction calculation is unnecessary. 7.5 Pump Down Times The pump down time is determined primarily by the pumping station volume flow rate and the recipient. Pump down time is also influenced by other factors such as the tightness of the complete 36 V p1 t = –– In ––– [h] S p2 By transforming equation 25, the following is obtained: V p1 S = –– In ––– t p2 12 1000 S = ––– In ––––– = 168 m3/h 0.3 15 V (m3) Volume of the recipient S (m3/h) Volume flow rate of the pumping station at the intake port Sv (m3/h) Volume flow rate of the backing pump p1,2 (mbar) Pressure (pressure range from p1 and p2) ∆p (mbar) Set pressure differential at the overflow valve of the Roots vacuum pump t (h) Pump down time This calculation shows that a volume flow rate of 168 m3/h at the recipient must be constant throughout the range 1000 mbar to 15 mbar. More often than not, pumping stations have volume flow rates that differ over the pressure range. In these cases there are a number of ways in which the pump down time can be determined. V p1 + ∆p t = –– In –––––––– = [h] S p2 + ∆p Equation 26 Example 9 Figure 22 shows the combined pump down time calculation of a tight, clean 200m3 chamber from 1000 mbar to 10-2 mbar according to a given volume flow rate curve. Procedure The method most commonly used in individual cases involves dividing the volume flow rate curve over the pressure in several partial ranges of pressure in which there is little variation in volume flow rate. For these individual pressure ranges, the partial pump down times with their respective mean volume flow rate must be calculated individually according to equation 25 and added to arrive at the total pump down time. An example of this is given in Figure 22, partial range 2 – 5. For the pressure range 1000 to 10 mbar (in Figure 22, Section 1) the partial pump down time t1 is calculated as per equation 26. For the pressure range 10 to 10-2 mbar equation 25 is applied in as much the volume flow rate is divided in the pressure range 2 to 5 and the individual pump down times t2 to t5 calculated. S [m3/h] Sometimes the volume flow rate for a particular pressure range can be expressed by an equation. This is, for example, the case with a Roots vacuum pump with open overflow valve. Depending on the staging to the backing pump, the range approx. 1000 to 10/20 mbar. An approximation to the volume flow rate here is: The total pump down time of tges ~ 3.3 hours under ideal conditions is arrived at by adding all partial pump down times t1 to t5. 5000 4000 3000 2000 Pump down time of a 200 m3 chamber. t1 = 200 1000 + 70 In 180 10 + 70 t2 = 200 In 1600 10 5 = 0.0870 h t3 = 200 In 2800 5 2 = 0.0654 h t4 = 200 In 3800 2 1 = 0.0366 h = 2.8800 h 200 1 In = 0.2050 h t5 = 4500 0.01 tges up 1000 to 10 mbar: = 3.2740 h 1000 0 10-3 10-2 55 4 10-1 100 3 2 101 S= 180 (p + 70) p t= V p1 + 70 In 180 p2 + 70 1 102 103 p [mbar] Fig. 22 Calculation of pump down times in stages 37 s [m3/h] Calculations Serf (m3/h) Required volume flow rate of the pumping station at the recipient 5000 1 4000 p (mbar) Working pressure 3000 mbar l qL = –––– s––– ( ) Total leak rate (of the system) 2000 1000 2 0 10-3 10-2 10-1 100 101 102 103 p [mbar] Fig. 23 The influence of the leak rate on the volume flow rate of a Roots vacuum pump. 1 Volume flow rate without taking the leak rate into account (as per example 9). 2 Volume flow rate taking the leak rate into account (as per Example 10). 7.6 The Influence of Leaks on Pump Down Times and End Vacuum (Leak Rate) Lack of tightness (leaks) in the whole system must be taken into account when the configuration of a vacuum pumping station is under consideration. The leak rate, which is expressed in mbar I/s, is calculated on the basis of known leak locations in feedthroughs and seals, etc. or by means of the pressure rise method. Taking the leak rate into account, the required volume flow rate at a specific pressure. 3.6 · qL Serf = ––––––– = [m3/h] p Equation 27 38 Example 10 given: leak rate qL = 11.68 mbar l/s Required: volume flow rate at 1 mbar, 10-1 and 10-2 mbar 3.6 · qL 3.6 · 11.68 Serf = –––––––– = –––––––––– = 42 m3/h p 1 at 1·10-1 mbar: Serf = 420 m3/h at 1·10-2 mbar: Serf = 4200 m3/h If the volume flow rate curve resulting from example 9 is compared with the curve which takes the leak rate into account (see Fig. 23), one can see that: – at 1 mbar the leak rate is negligible – at 10-1 the volume flow rate is reduced by approx. 10% – at 10-2 the volume flow rate is reduced by approx. 96%. If the pump down time is now recalculated using this leak rate, there is an increase in pump down time of approx. 50% from 0.205 h to 0.31 h between 1 and 10-2 mbar. The attainable final pressure of the pumping station according to example 9 (Figure 22) is limited to 9.4 x 10-3 mbar due to this leak rate. 7.7 Drying Process In a drying process, 40 kg of water, which evaporates at 20°C, has to be pumped off. In addition, 50 kg of air enters through a leak in the recipient. Explanation: Pressure p is assumed to be 10 mbar because at this pressure and at a temperature of 20°C water evaporates (see water vapor pressure curve in Figure 24). V (m3) (Gas-) volume 293 40 10 V = 83.14 –––– ––– + ––– 10 18 29 3 V = 6253 m ( T (K) Temperature or S = 6253 m3/“time units“ p (mbar) (Working) pressure R= ( mbar · m3 –––––––––– kmol · K ) Universal gas constant (R = 83.14) Example 11 Calculating the volume to be pumped off and the required volume flow rate at the intake port of the pumping station. Molar mass of water M1 = 18 kg/kmol water vapor pressure [mbar] ( ) kg –––––– kmol Molar mass of each component · Q (kg) Throughput of each component M= ) 103 solid liquid 102 evaporating melting 1 10 triple point (0.01° C, 6.09mbar) 100 Molar mass of air M2 = 29 kg/kmol sublimation Vapor pressure of water pD  23 mbar (at 20 °C) 10-1 gaseous Temperature (TC = 20 °C) T = 293 K 10-2 Pressure (selected according to the diagram) p = 10 mbar 10-3 Amount of water Q1 = 40 kg Leaked air Q2 = 10 kg 10-4 T Q1 Q2 V = R –– –– + –– + p M1 M2 ( Q3 ––– = [m3] M … n ) 10-5 -100 -80 -60 -40 -20 0 20 40 60 80 100 temperature [°C] Equation 28 Fig. 24 Vapor pressure curve of water (for example 11). 39 Calculations 7.8 Boyle-Mariotte Law p . V = constant 7.9 Selecting a Vacuum Pumping Station A pumping station should be assembled for a particular vacuum process. Known parameters are: vessel volume to be evacuated V = 1.6 m3 required final pressure p = 1 · 10-3 mbar p1 . V1 = p2 . V2 at T = constant Equation 29 p1 (mbar) (Start/atmospheric) pressure V1 (m3) Volume of gas at p1 p2 (mbar) Pressure (in vacuum) V2 (m3) Volume of gas atp2 Example 12 p1 = 1000 mbar V1 = 1 m3 V2 = ? Variables p2 a) p2 = 100 mbar b) p2 = 10 mbar c) p2 = 1 mbar d) p2 = 0.1 mbar p1 · V1 → V2 = ––––––– = [m3] p2 1000 mbar · 1 m3 a) V2 = –––––––––––––––– = 10 m3 100 mbar 1000 mbar · 1 m3 b) V2 = –––––––––––––––– = 100 m3 10 mbar 1000 mbar · 1 m3 c) V2 = –––––––––––––––– = 1000 m3 1 mbar 1000 mbar · 1 m3 d) V2 = –––––––––––––––– = 10000 m3 0.1 mbar 40 pump down time – t = 4 min  0.06 h Calculating the required volume flow rate V p1 t = –– · In ––– = [m3/h] S p2 t (h) Pump down time V (m3) Volume of the recipient S (m3/h) Volume flow rate p1 (mbar) (Start/atmospheric) pressure p2 (mbar) (Working/final) pressure V p1 S = –– · In ––– = [m3/h] t p2 1.6 1013 S = ––––– · In –––––– = 332 m3/h 0.06 0.001 Selection of the vacuum pumping station Explanation: S is the constant required volume flow rate of the vacuum pumping station over the whole pressure range of 1013 mbar (atmospheric) to 1 x 10 -3 mbar (Working/ final pressure). On the basis of the preceding calculation, a WOD 412 B (Figure 25) is selected. Checking the pump down time Caution! Pressure p2 (10 mbar) should be selected so that the overflow valve of the Roots vacuum pump (∆p = 53 mbar) is closed at the selected pressure ∆p. V p1 + ∆p = [h] t1 = ––– · In –––––––– p2 + ∆p Sv t (h) Pump down time 1.6 1013 + 53 t1 = ––– · In ––––––––– = 0.0665 h 68 10 + 53 t1 = 0.0665 h => t1 = 4 min* V (m ) Volume of the recipient 3 Sv (m3/h) Volume flow rate of the backing pump *) Based on the parameters, the pump down time for the vessel amounts to t = 4 min, that is, the volume flow rate of the backing pump . (S = 68 m3/h) is so small that t1 = t. p1 (mbar) (Start/atmospheric) pressure p1 p2 (mbar) (Compressed to) pressure p2 s [m3/h] ∆p (mbar) Differential pressure at the overflow valve 104 A B 103 C 332 D 10-3 10-1 S ≈ 300m3/h S ≈ 350m3/h 100 D t1 Sv = 68m3/h t2 10-2 t3 S ≈ 400m3/h S ≈ 300m3/h t4 101 10-4 t6 10 t5 S ≈ 250m3/h E 2 101 102 103 Intake pressure p [mbar] Fig. 25 Diagram for 7.9 (Selection of a pumping station) gas ballast valve of the backing pump closed. gas ballast valve of the backing pump open At 60 Hz operations, the volume flow rate increases by 20 %. Volume flow rate Roots vacuum pumps with two stages rotary vane vacuum pumps A WOD 3000B B WOD 1800 B C WOD 900 B (WKP 1000 A/DUO 120) D WOD 412 B (WKP 500 A/DUO 65) E WOD 222 B 41 Calculations V p1 t1 = ––– · In ––– = [h] p2 Sm Adding: tges = t1 + ... tn t (h) Pump down time (Theoretical, calculable pump down time with the vacuum pumping station – WOD 412 B –) V (m3) Volume of the recipient Sm (m3/h) Mean volume flow rate of the pump station from pressure p1 to p2 p1 (mbar) (from) pressure p1 p2 (mbar) (to) pressure p2 1.6 10 t2 = –––– · In ––– = 0.0049 h 300 4 1.6 4 t3 = –––– · In –– = 0.0063 h 350 1 1.6 1 t4 = –––– · In ––––– = 0.0156 h 400 0.02 1.6 0.02 t5 = –––– · In –––––– = 0.0086 h 300 0.004 1.6 0.004 t6 = –––– · In –––––– = 0.0089 h 250 0.001 → tges = 0.1108 h → tges = 6.6 min [tges – t1 = 6.6 – 4 = 2.6 min] Comparison Required pump down time/theoretical, calculable pump down time Required pump down time: t = 4 min Calculated pump down time: t = 6.6 min Selected vacuum pumping station WOD 412 B: WKP 500 A – Nominal volume flow rate: Sth = 490 m3/h (see 8.9) DUO 65 – Nominal volume flow rate: Sth = 62 m3/h (see 8.8.3) WOD 412 B is too small! The pump down time is too long because the volume flow rate, especially that of the backing pump, is too small (tges = 6.6 min.). WOD 900 B: WKP 1000 A — Nominal volume flow rate: Sth = 1070 m3/h DUO 120 — Nominal volume flow rate: Sth = 128 m3/h WOD 900 B is right! The volume flow rate is approx. twice that of the WOD 412 B and the pump down time therefore roughly halved. t ~ 3.5 min. < 4 min. 42 43 Appendix 8 Appendix 8.1 Graphic Symbols in Vacuum Technology The symbols for vacuum pumps are not position dependent. They can be turned in any direction. The higher pressure is on the narrower side. Vacuum gauges With the exception of the symbols for throughput quantities, the symbols for vacuum gauges are position dependent. The point of the angle signifying vacuum must always be facing down. Vacuum pump, general Gauge head Rotary vane vacuum pump Gauge operations and control unit Liquid ring vacuum pump Gauge operations and control unit with recorder Roots vacuum pump Flowmeter Vacuum pump accessories Separators, general Vacuum vessels Vacuum chamber Separators with heat exchanger (e. g. cooled) Vacuum bell jar Gas filters, general Filters, filter systems, general Baffles, general Vapor traps, general Cooling traps, general Cooling traps with coolant reservoir Sorption traps 44 Shut-off devices Symbols for shut-off devices are not position dependent. In flow diagrams, each attachment for connecting lines must be placed in the middle of the vertically drawn line. Symbols for angle valves must be entered in the diagram according to their actual position in the system. Shut-off device, general Shut-off valve Right angle valve Pipe Connections Stopcock Flange connection Three way Stopcock Flange connection, screwed Right angle Stopcock Small flange connection Gate valve Clamped flange connection Shut-off flap Threaded pipe connection Non-return valve Ground-in ball and socket joint Safety shut-off device Spigot and socket joint Operation of shut-off devices Taper ground joint Manual drive Dosing valve Altering the diameter of the conducting pipe Electromagnetic drive Cross-over of two conducting pipes with connecting point Hydraulic or pneumatic drive Cross-over of two conducting pipes without connecting point Branch-off point Electric motor drive Directional signs Weight driven Vacuum 45 Appendix flow is therefore dependent on the viscosity of the gas and may be laminar or turbulent. In the case of viscous flow the resistance is a function of the pressure. 8.2 Definition of terms A Absorption Absorption is a type of sorption in which the gas (absorbate) diffuses into the bulk of the solid or liquid (absorbent). Turbulent flow Turbulent flow (eddy flow) is a viscous flow with mixing motion above a critical Reynolds number (for circular cylindrical pipes Re = 2300). Adsorption Adsorption is a type of sorption in which the gas (adsorbate) is retained at the surface of the solid or liquid (adsorbent). Laminar flow Laminar flow (parallel flow) is a viscous flow without mixing motion at small Reynolds numbers. B Backing pump A backing pump generates the necessary low pressure required by the exhaust of some vacuum pumps. C Compression chamber The compression chamber is the space within the stator of some positive displacement pumps. It is the space where gas is compressed before being expelled. Compression ratio The compression ratio is the ratio between the outlet pressure and the inlet pressure of a pump for a specific gas. Cooling trap A cooling trap is a trap which affects condensation on a cooled surface. D Desorption Desorption is the movement of gases sorbed by a sorbent material. The movement can be spontaneous or can be accelerated by physical processes. Diffusion Gas diffusion is the movement of a gas in another medium owing to its concentration gradient. The medium may be gaseous, liquid or solid. F 46 G Flow Viscous flow Viscous flow is the passage of a gas through a duct under conditions such that the mean free path is very small in comparison with the smallest internal dimension of a cross section of the duct. The Molecular flow Molecular flow is the passage of a gas through a duct under conditions such that the mean free path is very large in comparison with the largest internal dimensions of a cross section of the duct. In the case of molecular flow, the resistance is independent of the pressure. Flow resistance In most applications, the vacuum pump is connected to the chamber via a pipe. This pipe exhibits a flow resistance which arises from the ratio pressure differential ∆p divided by the gas flow q. At high vacuum and ultra high vacuum, flow resistance is independant of the pressure. The unit is s · m-3, s · l-1. Fore vacuum pressure The fore vacuum pressure is the pressure required at the discharge side of a vacuum pump which cannot operate at atmospheric pressure. Gas Gas is matter in which the mean distance between the molecules is large in comparison to their dimensions and the mutual arrangement of the individual molecules is constantly changing. Gas is a gaseous state which has not been converted into a liquid or solid state by compression at the prevailing temperature and pressure. Gas ballast Inlet of a controlled quantity of gas, usually into the compression chamber of a positive displacement pump, so as to prevent condensation within the pump. Mass flow Mass flow is the mass of a gas flowing through a cross section of a pipe in a given time and the time span. It is equivalent to throughput. Gas liberation Gas liberation is spontaneous desorption. Mean free path The mean free path is the average distance which a molecule travels between two successive collisions with other molecules. M Gas load The gas load is the gas throughput delivered to a vacuum pump. The unit is mbar, l/s or sccm (standard cubic centimeters per minute). Standard conditions are 1013.25 mbar and 273.15 K (standard conditions). At 20°C, 1 mbar l/s = 55.18 sccm. Gettering Gettering means bonding of gas, preferably by chemical reactions. Getters (getter materials) often have large real surfaces. K L Normal conditions Normal conditions refer to the established standard temperature and standard pressure of a solid, liquid or gaseous substance. N Knudsen number The various types of flow are characterized by the ratio of the diameter of a pipe to the mean free path of the gas flowing through that pipe. This ratio is the Knudsen number Kn = I/d. Normal temperature Tn = 273,15 K δn = 0 °C Normal pressure Pn = 101325 Pa = 1013.25 mbar Occlusion Occlusion is the presence of a gas volume in solid particles or liquids (bubbles). This can occur in rotary vane pumps when a large amount of gas is pumped through the oil reservoir. Laminar flow Laminar flow is a viscous flow without inter-mixing at small Reynolds number levels. Leak Leaks in a vacuum system are holes or voids in the walls or at joints, caused by faulty material or machining or incorrect handling of the seals. Leak rate The leak rate is the throughput of a gas through a leak. It is a function of the type of gas, pressure difference and temperature. The unit for the leak rate is: 1 Pa · m3 · s-1 =1 W = 10 mbar · l · s-1 Multi – stage vacuum pumps Multi – stage vacuum pump refers to the sequential arrangement of pumping systems frequently located in a common housing and representing a constructive unit. Oil mist filter in vacuum pumps An oil separator in a vacuum pump is a device on the exhaust side of positive displacement pumps to trap and, in some cases, to return vacuum pump oil to the vacuum pump. If oil in droplet forms is involved, the device is referred to as an oil mist separator or oil mist filter. O Outgassing Outgassing is a spontaneous desorption. 47 Appendix P Partial pressure The partial pressure is the pressure due to a specified gas or vapor component of a gaseous and/or vapor mixture. R η ρ = density of fluid v = average flow velocity l = characteristic length = (e.g. pipe diameter) η = dynamic viscosity Re < 2300 : laminar flow Re > 4000 : turbulent flow Particle density Particle density is the quotient from the number of particles contained in a given volume. Permeation Permeation is the passage of gas through a solid barrier or a liquid of finite thickness. Permeation involves diffusion and surface phenomena. S Pressure The pressure of a gas on a boundary surface is the normal component of the force exerted by the gas on an area of a real surface divided by that area. Pressure units The legal pressure units are Pascal as the SI unit, abbreviation Pa, and bar as a special unit designation for 105 Pa. Saturation vapor pressure The saturation vapor pressure is the pressure exerted by a vapor which is in thermodynamic equilibrium with one of its condensed phases at the prevailing temperature. Sorption Sorption is the attraction of a gas (sorbate) by a solid or a liquid (sorbent). Sorbents are also called sorption agents. T 1 Pa = 1 Nm2 1 bar = 1000 mbar = 105 Nm-2 = 105 Pa. The unit commonly used in vacuum technology is the millibar. pV throughput pV throughout is the quotient from the pV value of a gas which in a given time span flows through the cross section of a pump at the prevailing temperature and the time span. pV value The pV value is the product of the pressure and the volume of a specified volume of a gas at the prevailing temperature. If the pV value is to be used as a measure for the volume of substance or gas, this must be an ideal gas at a specified temperature. 48 Reynolds number Non-dimensional quantity ρ·v·l Re = ––––––– Throughput rate Throughput rate of a vacuum pump is the pV flow of the pumped gas. Units of throughput rate are m3 · s-1, l · s-1, m3 · h-1. Total pressure The total pressure is the sum of all partial pressures present. This term is used in contexts where the shorter term “pressure” might not clearly distinguish between the individual partial pressure and their sum. Trap A trap is a device in which the partial pressure of an undesirable residue in a mixture of gas and/or vapors which is reduced by physical or chemical means. U V Ultimate pressure Ultimate pressure is the value which the pressure approaches asymptotically in a vacuum pump. Vacuum ranges mbar particle density rough vacuum (GV) 1000 – 1 2.5 · 1025 - 2.5 · 1022 m-3 ld medium vacuum (FV) 1 – 10 2.5 · 10 - 2.5 · 10 m ld Vacuum pump oil Vacuum pump oil is an oil used in oil sealed vacuum pumps to seal, cool and lubricate. high vacuum (HV) 10 –10 2.5 · 10 - 2.5 · 10 m ld < 2.5 · 10 m ld -3 -3 ultra high vacuum (UHV) <10 -7 22 -7 mean free path (l) 19 19 15 15 -3 -3 -3 Particle density figures are valid for a temperature of 20 °C. d = pipeline diameter Vacuum pump separators Separators, fitted either at the inlet or discharge side are devices to trap condensates which form in parts of the pump or vacuum lines when pumping vapors and solid substances. Vane The vane is a sliding component dividing the space (compression chamber) between the rotor and the stator in a positive displacement pump. W Vapor Vapor is a substance in gas phase which is either in thermodynamic equilibrium with its liquid or solid phase (saturated vapor) or brought to thermal equilibrium by compression (condensed) at the prevailing temperature (unsaturated vapor). Note: In vacuum technology, the word “gas” has been loosely applied to both the noncondensable gas and the vapor, if a distinction is not required. Volume throughput The volume throughput is the quotient from the volume of a gas which flows through the cross-section of a pipe in a given time at a specific pressure and a specific temperature, and the time span itself. Water vapor capacity CWo The water vapor capacity is the maximum volume of water per unit of time which a vacuum pump can continuously take in and discharge in the form of water vapor under ambient conditions of 20°C and 1013 mbar. Water vapor compatibility pWo Water vapor compatibility is the highest intake pressure under which a vacuum pump can deliver pure water vapor and not accumulate liquid water internally. Vapor pressure The vapor pressure is the partial pressure of the vapor. Volume flow rate The volume flow rate S is the average volume flow from a standardized test dome through the cross section of the pump’s intake port. Units for the volume flow rate are m3s-1, l · s-1, m3 · h-1, Torr · l · s-1 49 Appendix 8.3 Operating medium Description Application1) attainable final pressure (mbar)2) flash point (K) density (g/cm3) P3 Mineral oil Viscosity ISO-VG 100. The core fraction of a paraffin based oil type with low vapor pressure, without additives. Standard applications To pump off e.g.: Air, inert gases, noble gases, ammonia, weakaggressive solvent fumes, hydrogen, silane. 10-3 537 0.8 F5 Perfluoropolyether Viscosity ISO-VG 100. A polymer compound with low molecular weight and the structure of perfluoridated polyethers. F5 is biologically inert. To pump off Oxygen, ozone, halogens, uranium compounds, organic and inorganic solvents, HCL, BF3, HF, PH3 fluorine. 1 · 10-3 – 1.9 A555 Synthetic oil on esterbasis viscosity ISO-VG 100, high thermal, oxidative and chemical stability, excellent wear protection, high corrosion protection application with high operating temperatures > 100°C 5 · 10-2 525 0.96 RL 68 S polyol ester viscosity ISO-VG 68 Refrigerating unit oil. For pumping out coolant circuits in refrigerating units 2 · 10-2 518 0.97 Table 4 Operating medium 1) 2) 50 Applications involving other chemicals/substances 1) available on request. With two-stage rotary vane vacuum pump 8.4 Conversion Tables 8.4.1 Pressure Conversion Table mbar bar torr Pa (Nm-2) atm Ibf in-2 PSI kgf cm-2 in Hg mm Hg in H20 mm H20 1 mbar = 1 1 . 10-3 0.75 102 9.869 . 10-4 1.45 . 10-2 1.02 . 10-3 2.953 .10-2 0.75 0.402 10.197 1 bar = 103 1 7.5 .102 1 . 103 29.53 7.5 . 102 4.015 . 102 1.02 . 104 1 torr = . 1.333 1.333 10 1 Pa (Nm-2) = 0.01 1.013 . 103 1 atm = 1 Ibf in-2 PSI = 68.95 -3 0.987 . 2 14.5 . 1.316 10 -3 1.02 . 1.934 10 -2 . 1.36 10 -3 . 1.36 10 -2 1 1.333 10 1 0.535 13.59 1 . 10-5 7.5 . 10-3 1 9.87 . 10-6 1.45 . 10-4 1.02 . 10-5 2.953 . 10-4 7.5 . 10-3 4.015 . 10-3 0.102 1.013 7.6 . 102 1.013 . 105 1 14.7 1.033 29.92 7.6 . 102 4.068 . 102 1.033 . 104 6.805 . 10-2 1 7.03 . 10-2 2.036 51.71 27.68 7.03 . 102 3.937 . 102 104 6.895 . 10-2 51.71 6.895 . 103 9.807 . 102 0.981 7.356 . 102 9.807 . 104 0.968 14.22 1 28.96 7.356 . 102 1 in Hg = 33.86 3.386 . 10-2 25.4 3.386 . 103 3.342 . 10-2 0.491 3.453 . 10-2 1 25.4 13.6 3.45 . 102 1 mm Hg = 1.333 1.333 . 10-3 1 1.333 . 102 1.316 . 10-3 1.934 . 10-2 1.36 . 10-3 3.937 . 10-2 1 0.535 13.59 1 in H20 = 2.491 . . . . . 1 mm H20 = 9.807 . 10-2 9.807 . 10-5 1 kgf cm-2 = 2.491 10 -3 . 1.868 2.491 10 7.354 . 10-2 9.807 2 -3 3.613 10 9.677 . 10-5 1.42 . 10-3 2.458 10 -2 2.54 10 10-4 Table 5 -3 7.356 10 -2 2.896 . 10-3 1.868 1 25.4 7.354 . 10-2 3.394 . 10-2 1 also: 1 dyn cm-2 = 0,1 Pa (Nm-2) = 10-3 mbar 8.4.2 Leak Rate Conversion Table mbar l/s-1 1 mbar l/s-1 = torr l/s-1 1 -1 0.75 atm cm3 s-1 lusec atm ft3 min-1 1 kg/h air (20 °C) 0.987 7.5 . 102 2.097 . 10-3 4.3 . 10-3 . 5.7 . 10-3 3 -3 1 torr l/s = 1.333 1 1.316 10 2.795 10 1 atm cm3 s-1 = 1.013 0.76 1 7.6 . 102 2.12 . 10-3 4.3 . 10-3 1 lusec = 1.333 . 10-3 0.001 1.32 . 10-3 1 2.79 . 10-6 5.7 . 10-6 1 atm ft3 min-1 = 4.78 . 102 3.58 . 102 4.72 . 102 3.58 . 105 1 - 230 1.75 . 10-1 - 1 1 kg/h air (20 °C) = 230 175 Table 6 8.4.3 Volume Flow Rate l/s-1 l/min-1 ft3 min-1 m3/h-1 1 l/s-1 = 1 60 2.12 3.60 1 l/min-1 = 0.0167 1 0.0353 0.06 1 ft3 min-1 = 0.472 28.32 1 1.70 1 m3/h-1 = 0.278 16.67 0.5890 1 Table 7 Definition of the symbols Pa Pascal 2 N/mm Newton per square millimeter bar Bar mbar Millibar at Technical atmosphere kp/cm2 Kilopond per square centimeter mm /Ws Millimeter water column atm Physical atmosphere Torr Torr mmQs Millimeter mercury psi, Ibf/in2 English pound per square inch 51 Appendix 8.5 Data on Various Substances (Table 8) Compound Formula Helium Neon Argon Air Hydrogen Nitrogen Oxygen Fluorine Chlorine Hyrofluoric Acid Hydrochoric Acid Hydrobromic Acid Hydrogen Iodide Hydrocyanic Acid Water Hydrogen Sulfide Ammonia Nitrous Oxide Nitrous Oxide Nitrogen Tetroxyde Cyanogen Carbon Monoxide Carbon Dioxide Carbon Disulfide Sulfur Dioxide Sulfur Hexaflouride Methyl Fluoride Methylene Fluoride Fluoroform Tetraflouralmethane Methyl Chloride Methylene Chloride Chloroform Diflourochloromethane Fluorotrichloromethane Trifluorochloromethane Difluorodichloromethane Fluorotrichloromethane Ethyl Fluoride Ethyl Chloride Ethyl Bromide Trifluorotrichloroethane Tetrafluorodichloroethane Trifluorochloroethylene Vinyl chloride 11-Dichloroethylene Trichloroethylene Tetrachlroethylene Fluorbenzene Chlorobenzene Benzyl chloride Methane Ethane Propan Butane Pentane Hexane Heptane Octane Benzene Toluol Ethylbenzene o-Xylol m-Xylol p-Xylol Styrolene (Beinyl Benzene) i-Propyl Benzene Diphenyl Naphtalin Methanol Aethanol Propanol Butanol Pentanol Hexanol Heptanol Octanol i-Propanol i-Butanol i-Pentanol Ethylene Glycol 13-Propylene Glycol Glycerin Benzyl Alcohol Phenol Formic Acid Acetic Acid Monochloracetic Acid Dichloracetic Acid Trichloracetic Acid Ketene Acetone Formaldehyde Acetaldehyde Furfurol He Ne A 52 H2 N2 O2 F2 Cl2 HF HCl HBr HJ HCN H2O H2S NH3 NO N2O N2O4 C2N2 CO CO2 CS2 SO2 SF6 CH3F CH2F2 CHF3 CF4 CH3CI CH2CI2 CHCI3 CHF2CI CHFCI2 CF3CI CF2CI2 CHFCI3 C2H5F C2H5CI C2H5Br C3F3CI3 C2F4CI2 C2F3CI C2H3CI C2H2CI2 C2HCI3 C2CI4 C2H5F C6H5CI C7H7CI CH4 C2H6 C8H8 C4H10 C5H12 C6H14 C7H16 C8H18 C6H6 C7H8 C8H10 C8H10 C8H10 C8H10 C8H8 C9H12 C12H10 C10H8 CH4O C2H6O C3H8O C4H10O C5H12O C8H14O C7H18O C8H18O C3H8O C4H10O C5H12O C2H6O2 C3H8O2 C3H8O3 C7H8O C6H6O CH2O2 C2H4O2 C2H3O2CI C2H2O2CI2 C2H2O2CI3 C2H2O C3H6O CH2O C2H4O C5H4O2 Mol.Weight mol Standard Concentration kg/m3 Melting point °C Melting Temperature kJ/kg 4.00 20.18 39.94 28.96 2.02 28.02 32.00 38.00 70.91 20.01 36.47 80.92 127.93 27.03 18.02 34.08 17.03 30.01 44.02 92.02 52.04 28.01 44.01 76.13 64.06 146.06 34.03 52.03 70.02 87.99 50.49 84.94 119.39 86.48 102.93 104.47 120.92 137.38 48.06 64.50 108.98 187.39 170.93 116.48 62.50 96.95 131.40 165.85 96.10 112.56 126.58 16.04 30.07 44.09 58.12 72.14 86.17 100.19 114.22 78.11 92.13 106.16 106.16 106.16 106.16 104.14 120.19 154.20 128.16 32.04 46.07 60.09 74.12 88.14 102.17 116.19 130.22 60.09 74.12 88.14 62.07 76.09 92.09 108.13 94.11 46.03 60.05 94.50 94.50 94.50 42.04 58.08 30.03 44.05 96.08 0.18 0.90 1.78 1.29 0.09 1.25 1.43 1.70 3.17 0.98 1.63 3.64 5.79 (1.21) 0.77 1.54 0.77 1.34 1.97 (4.11) (2.32) 1.25 1.97 (3.40) 2.92 (6.52) 1.52 (2.32) (3.13) (3.93) 2.31 (3.79) (5.33) (3.86) (4.59) (4.66) (5.40) (6.13) (2.15) (2.88) (4.86) (8.37) (7.63) (5.20) (2.79) (4.33) (5.86) (7.40) (4.29) (5.02) (5.65) 0.72 1.35 2.01 2.70 3.45 (3.85) 4.46 5.03 (3.49) (4.11) (4.74) (4.74) (4.74) (4.74) (4.65) (5.36) (6.88) (5.72) (1.43) (2.06) (2.68) (3.31) (3.93) (4.56) (5.22) (5.81) (2.68) (3.31) (3.93) (2.77) (3.40) (4.11) (4.83) (4.20) (2.05) (2.68) (4.21) (4.21) (4.21) (1.88) (2.59) (1.34) (1.97) (4.29) -270.7 -248.6 -189.3 -213 -259.2 -210.5 -218.8 -220.0 -100.5 - 83.1 -1 1 1 .2 - 87.0 - 51.0 - 14.2 0.00 - 85.6 - 77.9 -163.5 - 90.8 - 1 1 .2 - 27.9 -205.0 - 56.6 -1 1 1 .5 - 75.5 - 50.7 3.52 16.75 29.31 -160 -183.6 - 97.7 - 96.7 - 63.5 -160 -135 -181 -155.0 -1 1 0.5 -136.4 -1 1 8.7 - 36.5 - 94.0 -157.5 -159.7 -122.5 - 86.4 - 22.4 - 41.9 - 45.2 - 39.2 -182.5 -183.3 -187.7 -138.4 -129.7 - 95.3 - 90.6 - 56.8 5.5 - 95 - 94.9 - 25.3 - 47.9 13.3 - 30.6 - 96.0 70.5 80.2 - 97.6 -114.2 -126.1 - 89.8 - 78.9 - 47.3 - 34.3 - 16.7 - 89.5 -108.0 -1 1 7.2 - 12.6 - 18.0 - 15.3 40.9 8.4 16.6 61.3 9.7 57.0 -151.0 - 94.8 - 92.0 - 123.5 - 36.5 58.63 25.75 13.82 37.69 188.45 228.65 56.12 30.99 23.03 31 1 .57 332.51 69.52 339.31 77.06 148.67 159.14 156.20 30.15 184.26 57.79 116.84 34.34 7.96 127.73 54.44 79.99 34.34 50.25 69.10 54.02 62.82 108.46 85.85 58.63 92.97 79.99 77.47 116.42 147.83 141.55 180.91 127.73 72.03 86.27 129.82 108.88 160.39 80.82 121.45 146.99 103.02 108.05 86.69 125.22 111.81 150.76 89.20 108.0 130.6 188.45 200.60 82.92 120.61 276.39 195.15 205.20 81.24 62.40 96.32 73.71 Boiling Evaporation at 1 bar Temperature Temperature °C kJ/kg -268.9 -246.1 -185.9 -192.3 -252.8 -195.7 -182.9 -188.0 - 34.0 19.9 -84.8 -66.5 -35.1 25.7 100.00 -60.4 -33.4 -151.7 - 88.7 21.1 -21.2 -191.6 -78.21) 46.3 -10.0 -63.51) -78.1 -52.0 -84.2 -127.7 -23.7 40.1 61.2 -40.8 8.9 -81.5 -29.8 23.7 -32.0 12.4 38.4 47.6 4.1 -27.9 -13.9 31.7 87.2 120.8 84.8 132.2 179.4 -161.5 -88.6 -42.1 -0.5 36.1 68.7 98.4 125.7 80.1 110.6 136.2 144.4 139.2 138.4 145.21) 152.4 256.1 217.9 64.7 78.3 97.2 117.9 137.8 157.7 175.8 195.2 82.3 577.92 502.54 197.3 214.2 290.0 205.4 182.20 100.7 118.1 189.5 194.4 195.6 -56.0 56.2 -21.0 20.2 161.7 20.94 104.70 159.14 196.83 460.66 201.01 213.58 159.14 259.64 1289.84 443.91 217.77 154.95 975.76 2257.22 548.60 1369.41 460.66 376.90 414.59 448.09 217.77 573.73 351.78 402.03 114.75 519.29 262.58 137.36 427.16 329.58 253.78 247.08 259.64 150.76 167.51 182.59 382.35 280.58 144.06 127.73 195.15 368.53 272.21 242.05 209.39 Temperature °C Critical Data Pressure bar -267.9 -228.4 -117.6 -140.7 -239.9 -147.1 -118.0 -129.0 146.0 230.2 51.0 91.9 150.8 183.5 374.2 99.6 132.4 -92.0 35.4 158.2 126.5 -138.7 31.0 277.7 157.6 84.1 86.8 84.7 54.8 225.6 95.0 115.0 67.2 74.2 103.3 60.1 35.7 75.3 75.5 80.4 44.9 59.9 -45.5 141.5 237.5 260.0 96.0 178.5 28.7 111.5 198.0 38.1 68.0 62.9 55.6 50.3 52.7 39.4 40.9 44.6 102.2 54.3 63.5 34.8 0.618 0.353 40.3 0.575 0.91 187.2 230.8 214.1 146.0 107.0 2.38 27.8 52.3 38.4 13.2 32.5 50.5 55.0 78.4 Specific Weight kg/l 0.065 0.484 0.531 0.310 0.031 0.311 0.441 0.573 0.610 0.807 0.195 0.329 0.235 0.520 0.459 0.507 0.311 0.468 0.441 0.524 0.496 0.522 0.555 0.554 51.2 0.330 0.507 324.97 286.5 359.2 46.1 46.1 0.354 0.365 510.49 489.97 426.32 385.70 357.64 335.02 316.60 301.10 394.49 355.96 339.63 347.59 343.40 339.21 -81.5 32.1 95.6 153.2 197.2 234.5 267.0 296.2 288.1 319.9 344.0 358.0 349.0 348.5 47.1 50.4 43.5 38.7 34.1 30.6 27.8 25.4 49.5 41.6 38.0 36.8 35.9 35.0 0.162 0.213 0.226 0.231 0.232 0.233 0.234 0.235 0.304 0.291 0.284 0.288 0.282 0.281 312.83 309.90 314.09 1101.39 845.94 753.80 590.48 515.10 636.55 439.72 410.40 670.05 277.6 306.6 812.43 362.7 495.6 478.5 232.8 234.3 265.8 287.1 315.0 32.2 32.9 40.5 81.3 64.4 51.8 50.0 0.343 0.314 0.275 0.276 0.273 825.00 466.94 510.91 494.16 406.22 265.93 322.88 523.48 711.93 573.73 452.28 365.3 385.5 273.5 49.8 54.9 419.2 62.5 321.5 59.0 0.351 235.0 48.6 0.252 188.0 Boiling Temperature at Various Formula 1 Pressure in mbar 40 100 200 Specific Temperature of Vapors Under Constant Pressure Within Range of 0 - 1 bar kJ/kg °C Temperature in °C 50 0 25 100 200 10 20 500 1000 -271.73 -271.54 -257.53 -255.9 -218.93 -214.7 -271.38 -255 -212.1 -271.18 -254 -209.2 -270.88 -253 -206.2 -270.45 -251.5 -202 -269.97 -250.2 -197.8 269.35 -248.2 -191.2 H2 -263.43 -262 N2 -226.83 -222.25 O2 -220.00 -214.5 F2 -223.93 -218.1 CI2 -120.00 -108.8 HF (app.-96.3) - 78.5 HCI -152.53 -142.6 HBr -140.63 -129.7 HJ -125.23 -112.2 HCN - 73.33 - 58.2 H2O - 20.00 - 2.7 H2S -136.00 -124.7 NH3 -110.83 - 99.6 NO -185.23 -181.2 N2O -144.80 -135.2 N2O4 - 57.60 - 45 C2N2 - 97.83 - 85.5 CO -222.73 -218.2 CO2 -126.3 -135.93 CS2 - 76.73 - 57.9 SO2 - 97.53 - 85.4 SF6 -134.53 -122.9 CH3F -148.93 -139.2 CH2F2 CHF3 CF4 -186.53 -176.2 CH3CI -102.53 - 95.4 CH2CI2 - 72.63 - 55.5 CHCI3 - 61.00 - 42.5 CHF2CI -124.73 -112.6 CHFCI2 - 93.83 - 78.5 CF3CI -151.13 -141.2 CF2CI2 -120.73 -107.3 CFCI3 - 86.83 - 70.8 C2H5F -119.13 -106.5 C2H5CI - 92.23 - 77 C2H5Br - 77.00 - 60 C2F3CI3 - 70.93 - 53 C2F4CI2 - 97.93 - 82.9 C2F3CI -118.00 -105.2 C2H3CI -108.00 - 93.7 C2H2CI2 - 80 - 63.3 C2HCI3 - 46.83 - 26.8 C2CI4 - 24.00 - 2 C6H5F - 46.53 - 26.8 C6H5CI - 16.73 6 C7H7CI - 18.00 43 CH4 -206.93 -200.3 C2H6 -161.23 -150.7 C3H8 -130.93 -118.1 C4H10 -103.93 - 88.7 C5H12 - 78.93 - 65.1 C6H14 - 56.23 - 38 C7H18 - 37.23 - 16.7 C8H16 - 17.33 6 C6H6 - 39.53 - 22.8 C7H6 - 30.00 - 9 C8H8 - 13.53 9.3 C8H10 - 7.53 15.6 C8H10 - 10.53 12.2 C8H10 - 11.63 10.5 C8H8 - 10.73 13.3 C8H12 - 0.63 22 C12H12 65.83 96 C10H8 - 49.23 70 CH4O - 46.83 - 28.9 C2H6O - 34.73 - 15.5 C3H8O - 18.00 1.1 C4H10O - 4.533 16 C5H12O - 10.23 30.5 C8H14O 20.93 42.9 C7H18O 393 60 C8H18O 50.33 72 C3H8O - 29.13 - 10.8 C4H10O - 12 7.1 C5H12O 6.8 26.9 C2H6O2 49.2 74.5 C3H8O2 55 82 C3H8O3 121.3 148.2 C7H8O 54.5 76.2 C6H6O 36.7 58.3 CH2O2 - 22.5 - 7.9 C2H4O2 - 20.8 1.7 C2H3O2CI 39.1 63.5 C2H2O2CI2 40 64.9 C2HO2CI3 47.2 71.3 C2H2O (-131.8) (-120.3) C3H6O - 62.2 - 44 CH2O - 113.3 - 98.5 C2H4O - 83.8 - 68.4 C5H4O2 14.8 38 -261.4 -220 -212 -215.3 -103.5 - 69.5 -137.8 -124.2 -105.3 - 50.9 6.9 -119 - 94.2 -179.2 -130.7 - 39.2 - 79.5 -215.9 -121.7 - 48.9 - 79.3 -117 -133.8 -260.5 -216.7 -209 -212.25 - 96.7 - 60.0 -132.4 -118 - 98 - 43 17.7 -112.5 - 88.5 -176.5 -125.9 - 33 - 73 -213.6 -116.5 - 38.8 - 72.7 -111.2 -128.4 -259.7 -215.2 -205.5 -209.7 - 88.0 - 49.7 -126.5 -111.2 - 89.5 - 34.5 29.2 -105.4 - 81.9 -173.3 -120.7 - 26.6 - 65.8 -211.1 -111.1 - 27.5 - 64.5 -104.5 -122.1 -258 -211 -200.4 -204.3 - 75.5 - 33.5 -117 -101 - 76.5 - 22 45.9 - 95 - 72 -167.9 -112.8 - 17.5 - 55.4 -207.1 -102.9 - 10.5 - 51.3 - 94.3 -112.2 -256.4 -207.4 -196 -200 - 64.6 - 19.2 -109 - 92.1 - 65.4 - 10.6 60 - 86.2 - 61.7 -164 -106.3 - 8.8 - 46.4 -203.2 - 96 4.2 - 40.5 - 86.3 -103.6 -254.5 -201.5 -189.2 -193.9 - 48.1 1.5 - 96.2 - 79 - 49.5 9 81.8 - 72.8 - 46.5 -157.3 - 96.7 7 - 33.7 -196.9 - 86.4 26.1 - 24 - 73.7 - 90.4 -268.9 -246.1 -185.9 -192.3 -252.8 -195.7 -182.9 -188 - 34 19.9 - 84.8 - 66.5 - 35.1 25.7 100 - 60.4 - 33.4 -151.7 - 88.7 21.1 - 21.2 -191.6 - 78.2 46.3 - 10 - 63.5 - 78.1 - 52 - 84.2 -127.7 5.20 1.03 0.52 1.01 13.51 1.04 0.91 0.80 0.46 40.1 61.2 - 40.8 8.9 - 81.5 - 29.8 23.7 - 32 12.4 38.4 47.6 4.1 - 27.9 - 13.9 31.7 87.2 120.8 84.8 132.2 179.4 -161.5 - 88.6 - 42.1 - 0.5 36.1 68.7 98.4 125.7 80.1 110.6 136.2 144.4 139.2 138.4 145.2 152.4 256.1 217.9 64.7 78.3 97.2 117.9 137.8 157.7 175.8 195.5 82.3 108 130.6 197.3 214.2 290 205.4 182 100.7 118.1 189.5 194.4 195.6 0.53 He Ne A 5 Pressure in °C -171.4 - 88 - 47 - 33.5 -106.5 - 71 -136.2 -100.6 - 62.5 -100.3 - 69.5 - 51.4 - 44 - 75.5 - 98.7 - 86.5 - 55 - 16.8 8.8 - 16.8 17.5 55.5 -197 -145.2 -111.5 - 81 - 55.2 - 29 - 6.7 14.7 - 14.8 1.8 21 27 23.5 22.2 25.5 33.6 110.5 81 - 20 - 6.4 10.2 26 40.3 53.5 70 83.3 - 1.4 17 36.6 86.8 95 161.5 87.5 69 - 0.7 12.7 75.5 77.3 83 (-114.3) - 35.2 - 91.2 - 60.4 49.5 -166.7 -161.1 -153.3 -146.5 -136.2 - 80 - 67 - 56 - 39 - 23.7 - 37.3 - 26.7 - 11.5 2.3 22.7 - 23.2 - 12 4.9 19.5 41 - 99.5 - 91.8 - 80.4 - 70.3 - 54.7 - 62.2 - 52.8 - 38.6 - 26.3 - 7.5 -131 -124.7 -114.8 -106.2 - 93.5 - 93.2 - 85.3 - 72.8 - 61.7 - 45 - 53.8 - 43.8 - 28 - 14.9 5.5 - 93.3 - 85.3 - 73.3 - 62.8 - 46.8 - 60.7 - 51.2 - 36.8 - 24.5 - 5.3 - 41.8 - 31.5 - 15 - 1.5 19.3 - 33.9 - 23.2 - 7.5 7 28.5 - 67 - 58 - 43.8 - 31.9 - 14 - 91.5 - 83.3 - 71 - 60 - 43 - 79.1 - 70.7 - 57.5 - 46.3 - 29.1 - 45.8 - 35.5 - 20.1 - 6.7 13.5 - 5.6 6.3 24.9 41 65.5 21 34.5 54.2 72 98 - 6 6.2 24.5 40 63.8 30 43.5 63.8 81.5 108.3 69 84 106.3 125.6 154 -193.3 -189.4 -183.5 - 178 -169.4 -139.3 -132.7 -122.8 -114 -100.7 -104.1 - 96 - 83.8 - 73.1 - 57 - 72.7 - 63.3 - 49 - 36.5 - 17.8 - 44.3 - 33.9 - 17.7 - 4.2 16.7 - 18.6 - 7.3 10 25 46.8 4.6 16.8 35.6 51.7 76 26.5 39.5 59 76.3 102 - 6 3.3 20 35.5 58.7 13.3 26.2 45.3 61.8 87.7 33.5 46.7 67.6 85.3 111.7 39.5 53.30 74 92 120 35.5 49.5 70 88 114.5 34.7 48.2 68.7 86.8 113.7 38.8 53.5 75 93.5 121 46 60 81 99 127 127 144.5 171.1 194 227.2 95 111.5 136.5 158 190 - 10.5 0.3 16 29.8 48.2 3.5 14 29.5 42.5 61 20.5 31.8 47.5 61 80.5 36.7 48.2 64.5 78.3 99.8 51 62.8 80.2 95 118.5 65.2 78.1 96.5 112.5 136 81.2 93.9 113.3 129.4 154 95.9 109.3 129 145 172 8.2 19.1 34.7 47.3 66.4 27.8 39 55.6 70 90 47.2 58 75 89.9 111.8 100 114 135 151.5 176.5 109 124.5 146 164.5 191.5 176 191.3 213. 231.5 261 100 113.9 134.7 152 181 81 94 114.5 131.5 158 7 18.3 37.3 54 78.5 24.6 37.3 56.3 73 97 88.5 102.5 123.8 141.5 167.2 90.5 105.2 127 145 171.9 96 110 130.5 148.1 173 (-108)(-101) (-90.6) (-81.8)(-68.2) - 56 - 25.1 - 14.1 2.3 16.2 37 - 83 - 74.4 61.5 - 50.6 - 34.3 - 51.5 - 42 - 27.4 - 15 3.5 62 76 96.5 114 140 0.80 0.36 0.23 1.29 1.84 0.99 2.06 0.97 0.86 0.82 1.07 1.04 0.82 0.58 0.59 0.60 5.20 1.03 0.52 1.01 14.34 1.04 0.91 0.82 0.48 1.44 0.80 0.36 0.23 1.33 1.84 1.01 2.09 0.97 0.88 0.86 1.10 1.04 0.85 0.60 0.61 0.64 5.20 1.03 0.52 1.01 14.41 1.04 0.93 0.86 0.49 1.46 0.80 0.36 0.23 1.41 1.88 1.03 2.22 0.98 0.95 0.95 1.17 1.04 0.93 0.64 0.66 0.75 5.20 1.03 0.52 1.02 14.41 1.05 0.96 0.90 0.51 1.46 0.80 0.36 0.23 1.52 1.94 1.08 2.37 1.01 1.02 1.05 1.17 1.06 1.00 0.68 0.71 0.55 0.50 0.72 0.77 0.59 0.53 0.64 0.57 1.10 0.84 0.76 0.81 0.61 0.55 0.67 0.59 1.24 0.96 0.87 0.92 0.69 0.61 0.75 0.67 0.49 0.51 0.55 0.54 0.57 0.56 0.64 0.61 0.58 0.59 1.27 0.59 0.62 0.64 1.31 0.62 0.64 0.66 1.47 0.72 0.70 0.74 0.81 0.67 0.60 0.58 0.86 0.71 0.63 0.60 1.00 0.80 0.70 0.64 1.16 0.89 0.76 0.69 2.17 1.65 1.55 1.60 1.60 1.61 1.61 1.61 0.95 1.03 1.11 1.16 1.11 1.11 1.08 1.16 2.23 1.75 1.67 1.70 1.70 1.70 1.70 1.71 1.05 1.13 1.21 1.26 1.20 1.20 1.17 1.26 2.45 2.07 2.02 2.03 2.03 2.03 2.03 2.03 1.34 1.42 1.51 1.52 1.48 1.47 1.45 1.57 2.81 2.49 2.46 2.45 2.45 2.44 2.44 2.44 1.68 1.76 2.06 1.86 1.83 1.81 1.77 1.93 1.34 1.52 1.38 1.41 1.60 1.49 1.60 1.83 1.80 1.43 1.52 4.44 4.50 0.36 0.23 1.23 0.98 1.99 0.97 0.82 1.04 0.77 0.55 0.50 2.07 1.48 1.31 1.26 1.22 1.19 1.17 1.15 1.09 56.2 - 21 20.2 161.7 5.20 1.03 0.52 1.01 14.05 1.04 0.91 0.82 0.47 1.14 1.24 1.15 1.18 Dynamic viscosity of the Vapors in 10-5 Pa·s Temperature in °C -50 0 25 100 200 1.66 2.64 1.83 1.49 0.744 1.44 1.66 1.89 3.05 2.16 1.74 0.856 1.69 1.96 2.01 3.18 2.32 1.87 0.908 1.81 2.09 2.34 3.72 2.76 2.22 1.05 2.12 2.49 2.75 4.34 3.27 2.64 1.23 2.51 2.96 1.25 1.37 1.71 2.14 1.34 1.76 0.67 0.92 1.19 0.948 1.83 1.39 1.48 1.73 1.93 0.76 1.01 1.29 1.02 1.96 1.52 1.87 1.89 2.43 1.00 1.31 1.62 1.31 2.32 1.87 2.35 2.39 2.99 1.33 1.69 0.96 0.948 1.69 1.41 0.92 1.19 1.02 1.81 1.51 0.99 1.31 1.29 2.14 1.89 1.28 1.66 1.45 1.11 1.00 1.06 0.78 0.67 0.85 0.74 0.983 0.923 0.989 0.938 0.955 1.19 1.08 1.10 1.03 1.05 1.29 1.15 1.39 1.29 1.32 1.60 1.39 0.71 0.67 1.01 0.865 1.18 1.03 1.26 1.11 1.52 1.36 0.955 1.05 1.32 0.872 0.937 0.986 1.09 1.05 1.17 1.22 1.41 0.862 0.729 1.04 0.877 0.765 0.703 0.632 0.601 1.12 0.953 0.831 0.759 0.694 0.663 0.714 0.826 0.704 1.36 1.17 1.03 0.969 0.877 0.838 0.731 0.689 0.970 0.908 1.11 1.06 0.938 0.862 1.22 1.14 1.84 2.11 2.17 0.887 0.765 0.694 0.975 0.850 0.762 1.24 1.11 0.949 1.59 1.41 1.26 1.82 2.17 0.714 0.772 0.970 1.28 4.63 6.17 3.96 0.877 1.38 1.29 1.32 1.17 1.24 1.46 1.56 1.26 1.42 1.84 1.41 1.68 0.949 1.23 0.775 1.45 1.17 1.68 2.73 2.29 2.52 2.34 1.63 2.11 1.79 1.63 1.63 1.63 0.95 0.673 0.739 1.64 1.45 1.28 53 Appendix 8.6 Desorption Rates on Clean Surfaces Material Surfacequality blank polished pickled bead blasted polished polished Stainless steel Stainless steel Stainless steel Stainless steel Steel Ni plated Steel Cr plated Steel Steel Steel Aluminium Brass Copper Porcelain Glass Acrylic glass Neoprene Perbunan Viton Viton Viton Teflon Surface condition cleaned cleaned heated for 1 hour, vented with normal air cleaned cleaned rusted cleaned cleaned cleaned cleaned cleaned blank bead blasted glazed cleaned heated for 4 hours at 100 °C heated for 4 hours at 150 °C degassed Table 9 Desorption rates for clean surfaces 1) a 0.8 0.6 0.4 0.2 0 1.2 1.4 1.6 1.8 2 2.2 2.4 pv /p Fig. 26: Correction Factor a Calculation of the fore vacuum dependent volumetric efficiency rating for a Roots vacuum pump. 54 mbar · l s · cm2 4h 2.7 . 10-7 2 . 10-8 1.4 . 10-9 3 . 10-10 2 . 10-7 1.3 . 10-8 6 . 10-7 5 . 10-7 4 . 10-7 6 . 10-8 1.6 . 10-6 3.5 . 10-7 8.7 . 10-7 4.5 . 10-9 1.6 . 10-6 4 . 10-5 4 . 10-6 1.2 . 10-6 1.2 . 10-7 1.2 . 10-9 8 . 10-7 5.4 . 10-8 4 . 10-9 2.8 . 10-10 6.5 . 10-11 1.5 . 10-8 2.2 . 10-9 1.6 . 10-7 1 . 10-7 8 . 10-8 1.7 . 10-8 5.6 . 10-7 9.5 . 10-8 4 . 10-7 1.1 . 10-9 5.6 . 10-7 2.2 . 10-5 1.7 . 10-6 3.6 . 10-7 5 . 10-8 3.3 . 10-10 2.3 . 10-7 [ ] 10h 2.7 . 10-8 2 . 10-10 1.4 . 10-10 4 . 10-11 5 . 10-9 1.2 . 10-9 1 . 10-7 5 . 10-8 3.8 . 10-8 1.1 . 10-8 4 . 10-7 5.5 . 10-8 2.8 . 10-7 5.5 . 10-10 4 . 10-7 1.5 . 10-5 1.3 . 10-6 2.2 . 10-7 2.8 . 10-8 2.5 . 10-10 1.5 . 10-7 The desorption rates can be disproved by different types of pretreatment (e.g. annealing for hydrogen removal). 8.7 Correction Factor a 1 Desorption rates1) qDes 1h 8.8 8.8.1 Technical Data, Rotary Vane Vacuum Pumps Rotary Vane Vacuum Pumps UNO 2.5 and UNO 5 Single-stage Connection nominal diameter Inlet Outlet Volume flow rate 50 Hz 60 Hz Ultimate pressure total without gas ballast total with gas ballast Water vapor tolerance Water vapor capacity Noise without gas ballast with gas ballast Operating temperature1) Operating medium quantity Rotation speed 50 Hz 60 Hz Motor rating Weight 8.8.2 UNO 2.5 UNO 5 A DN 16 ISO-KF DN 16 ISO-KF DN 16 ISO-KF DN 16 ISO-KF m3/h m3/h 2.5 2.9 4.6 5.1 mbar mbar mbar g/h <5 .10-2 <1 15 37 <5 .10-2 <1 20 75 dB(A) dB(A) °C I 53 55 80 0.45 53 55 80 0.45 rpm rpm kW kg 2800 3355 0.13 10.2 2800 3355 0.13 11 Rotary Vane Vacuum Pumps UnoLine Single-stage Connection nominal diameter Inlet Outlet Volume flow rate 50 Hz 60 Hz Ultimate pressure total without gas ballast total with gas ballast Water vapor tolerance Water vapor capacity Noise without gas ballast with gas ballast Operating temperature1) Operating medium Motor rating 50 Hz 60 Hz Rated rotation speed pump 50 Hz 60 Hz Weight, with three-phase motor UNO 35 UNO 65 UNO 120 UNO 250 DN 40 ISO-KF DN 40 ISO-KF DN 40 ISO-KF DN 40 ISO-KF DN 63 ISO DN 63 ISO DN 100 ISO DN 100 ISO m3/h m3/h 35 42 65 72 128 154 267 320 mbar mbar mbar g/h <5 . 10-2 <1 30 700 <5 . 10-2 <1 30 1400 <3 . 10-2 <1 33 3650 <3 . 10-2 <1 33 6950 dB(A) dB(A) °C I 54 56 80 4.5 54 56 80 5.4 58 60 90 17 60 61 90 30 kW kW 1.1 1.3 1.1 1.3 4 4 7.5 7.5 rpm rpm kg 1390 1660 50 1390 1660 60 965 1158 193 960 1152 375 1) At ambient temperature 25 °C and operating medium P3, without gas ballast. 55 Data compilation 8.8.3 Rotary vane vacuum pumps DuoLine Pump Connection nominal diameter Inlet Outlet Volume flow rate 50 Hz 60 Hz Ultimate pressure total without gas ballast with gas ballast Water vapor tolerance Water vapor capacity Noise without gas ballast with gas ballast Operating temperature Operating medium quantity Rotation speed 50 Hz 60 Hz Motor rating 50/60 Hz Weight 8.8.4 DUO 35 DUO 65 DUO 120 DUO 250 DN 16 ISO-KF DN 16 ISO-KF DN 40 ISO-KF DN 40 ISO-KF DN 40 ISO-KF DN 40 ISO-KF DN 63 ISO-KF DN 63 ISO-KF DN 100 ISO-KF DN 100 ISO-KF m3/h m3/h 2.5 2.9 32 38 62 70 128 154 250 300 mbar mbar mbar g/h <0.006 <0.006 15 37 <0.003 <0.005 20 500 <0.003 <0.005 20 1000 <0.003 <0.006 20 2300 <0.003 <0.006 30 4800 dB(A) dB(A) °C l 53 61 62 80 4.2 58 60 80 0.4 61 64 80 3.2 90 13 90 23 rpm rpm kW kg 2790 3280 0.13/0.13 10.3 1390 1660 1.1/1.25 56 1390 1660 1.5/1.8 65 960 1150 4 215 975 1175 7.5 410 DUO 5 DUO 10 DUO 20 UNO 30 M DN 16 ISO-KF DN 16 ISO-KF DN 25 ISO-KF DN 25 ISO-KF DN 25 ISO-KF DN 25 ISO-KF DN 25 ISO-KF DN 25 ISO-KF m3/h m3/h 5 6 10 12 20 24 30 35 mbar mbar mbar g/h <0.005 <0.02 36 230 <0.005 <0.01 30 230 <0.005 <0.01 30 460 <0.08 <1 8 190 dB(A) dB(A) °C l 55 55 57 60 80 0.75 80 1 85 1.2 80 1.1 rpm rpm kW kg 1390 1620 0.25/0.37 19 1400 1680 0.45/0.55 28 1390 1620 0.55/0.65 30 1390 1690 0.75 44 Rotary vane vacuum pumps, Magnetic Coupled Single-stage / Two-stage Connection nominal diameter Inlet Outlet Volume flow rate 50 Hz 60 Hz Ultimate pressure total without gas ballast with gas ballast Water vapor tolerance Water vapor capacity Noise without gas ballast with gas ballast Operating temperature Operating medium quantity Rotation speed 50 Hz 60 Hz Motor rating 50/60 Hz Weight 56 DUO 2.5 8.8.5 Rotary vane vacuum pumps PacLine Pump Connection nominal diameter Inlet Outlet Volume flow rate 50 Hz m3/h 60 Hz m3/h Ultimate pressure total without gas ballast mbar Noise without gas ballast dB(A) Operating medium quantity l Rotation speed 50 Hz rpm 60 Hz rpm Motor rating 50/60 Hz KW Weight kg 8.8.6 PAC 20 PAC 250 PAC 400 DN 25 ISO-KF DN 40 ISO-KF DN 40 ISO-KF DN 63 ISO-F DN G2" DN 63 ISO-F DN G2" DN 100 ISO-F DN 100 ISO-F DN 63 G 21/2" DN 63 G 21/2" 18 54 64 81 94 180 210 230 270 400 460 600 680 <2 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 70 0.5 70 2 75 2 80 6 80 6 80 17 80 17 2800 1450 1700 1.5/2.2 58 1450 1700 2.2/3 76 1450 1740 5.5/6.5 170 1450 1740 7.5/9 185 960 1150 11/13.2 420 975 1170 15/18 540 0.75 20 PAC 60 PAC 90 PAC 200 PAC 630 Rotary vane vacuum pumps BA 251 and BA 501 Pump Connection nominal diameter Inlet Outlet Nominal volume flow rate Volume flow rate at 50 Hz Ultimate pressure total without gas ballast total with gas ballast Water vapor tolerance Water vapor capacity Noise without gas ballast with gas ballast Operating temperature Cooling water requirement Operating medium quantity Rotation speed Motor rating Weight with motor BA 251 BA 501 m3/h m3/h DN 63 ISO-F DN 63 ISO-F 270 250 DN 100 ISO-F DN 100 ISO-F 545 500 mbar mbar mbar kg/h <6 . 10-2 <6 . 10-1 30 7 <6 . 10-3 <6 . 10-1 30 14 dB(A) dB(A) °C l/h I rpm kW kg 63 65 80 50 17 490 11 570 63 65 80 90 45 345 15 1100 57 Data compilation 8.9 8.9.1 Technical data Roots Vacuum Pumps WKP Pumps Nominal volume flow rate 50 Hz 60 Hz Starting pressure Differential pressure at overflow valve Leak rate Pump with radial shaft seals Pump with canned motor Rotation speed 50 Hz 60 Hz Motor rating 50 Hz 60 Hz Motor rating with canned motor 50 Hz 60 Hz Materials – rotor and casing Oil filling Weight with motor, approx. A: Standard pump with standard motor AD: Pressure surge-protected model with 8.9.2 WKP 250 A WKP 500 A WKP 1000 A/AD WKP 2000 A/AD m3/h m3/h mbar mbar 270 324 1013 53 490 590 1013 53 1070 1284 1013 43 2065 2478 1013 35 mbar . l/s mbar . l/s <1 . 10-2 <1 . 10-5 <1 . 10-2 <1 . 10-5 <1 . 10-2 <1 . 10-5 <1 . 10-2 <1 . 10-5 rpm rpm 3000 3600 3000 3600 3000 3600 3000 3600 kW kW 0.75 1.1 1.5 2.2 3 4 5.5 7.5 kW kW 1.5 1.7 GGG/GGL 1.5 1.7 GGG/GGL l kg 1.5 95 1.5 125 5 5.5 5.7 5.7 GGL(A) GGG/GGL (A) GGG/GGG 40.3 (AD) GGG/GGG 40.3 (AD) 3 5 250 370 Roots Vacuum Pumps with magnetic coupling WKP with magnetic coupling 500 AM/ADM Nominal volume flow rate 50 Hz m3/h 490 60 Hz m3/h 590 Starting pressure mbar 1013 Differential pressure at overflow valve mbar 53 Leak rate Pump with magnetic coupling mbar · l/s < 1 · 10-5 Noise level (DIN 45635) db(A) 70-75 Rotation speed 50 Hz rpm 2860 60 Hz rpm 3430 Motor rating 50 Hz kW 1.5 60 Hz kW 2.2 Operating medium quantity l 1.5 Weight, pump Standard motor approx. kg 130 Pump without motor approx. kg 110 AM: Standard pump with magnetic coupling ADM: Pressure surge-protected model with magnetic coupling 58 1000 AM/ADM 2000 AM/ADM 4000 AM/ADM 6000 AM/ADM 1070 1284 1013 43 2065 2478 1013 35 4050 4860 1013 25 6070 7280 1013 20 < 1 · 10-5 72-75 < 1 · 10-5 72-75 < 1 · 10-5 74-79 < 1 · 10-5 74-79 2860 3430 2860 3430 2900 3480 2900 3480 3 4 3 5.5 7.5 5 11 15 6.8 15 18.5 6.8 250 220 380 320 630 540 850 750 WKP 4000 A/AD WKP 6000 A/AD WKP 8000 WKP 12000 WKP 18000 WKP 25000 4050 4860 1013 25 6075 7290 1013 20 8000 9600 1013 27 12000 12000 1013 18 17850 21420 1013 10 25000 25000 1013 7 <1 . 10-2 – <1 . 10-2 – <1 . 10-2 – <1 . 10-2 – <1 . 10-2 – <1 . 10-2 – 3000 3600 3000 3600 1500 1800 2250 2250 1500 1800 2100 2100 11 15 15 18.5 22 30 30 30 45 55 55 55 5.5 5.7 GGG/GGL (A) GGG/GGG 40.3 (AD) 5 380 GGG/GGL (A) GGG/GGG 40.3 (AD) 6.8 850 GGL GGL GGL GGL 21 1600 21 1950 68 3100 68 4000 8.9.3 Gas cooled Roots Vacuum Pumps WGK Pumps Nominal volume flow rate 50 Hz 60 Hz Ultimate pressure Maximum Motor rating Rotation speed 50 Hz 60 Hz Noise level1) Noise frequency Oil filling Endplates heatable Sealing gas connection Materials Rotors and casing Seals Weight - Pump without drive Cooler and base frame WGK 500 WGK 1500 WGK 4000 WGK 8000 m3/h m3/h mbar kw 520 620 130 18.5 1500 1800 130 2 x 30 4600 5500 130 132 8000 9600 200 rpm rpm dB(A) Hz l 3000 3600 75 - 105 200 3 Yes Yes 1500 1800 75 - 105 100 5 Yes Yes 1500 1800 75 - 105 100 21 No Yes 1500 1800 75 - 105 100 21 No Yes GGG Viton GGG Viton GGG Viton GGG Viton 116 520 1100 1500 kg 130 1) These values depend on the operating pressure range or the differential pressure. 59 Data compilation 8.10 Technical Data Roots Vacuum Pumping Stations 8.10.1 Series WKD WKD 220 Volume flow rate at 10-1 mbar 50 Hz m3/h 220 60 Hz m3/h 265 Pumping station components Roots vacuum pump WKP 250 A Intermediate condenser KS 0.2 Single-stage rotary vane vacuum pump UNO 35 Total pressure without gas ballast mbar 1 · 10-3 with gas ballast mbar 2 · 10-2 Water vapor capacity mbar 33 Installed motor rating1) 50 Hz kW 1.85 60 Hz kW 2.2 Condenser cooling surface 0.2 Water cooling for backing pump – Cooling Water requirement2) rpm 4 Cooling water monitor in backing pump – Oil filling, complete l 4.2 Weight kg 260 WKD 410 WKD 900 WKD 1800 WKD 3000 WKD 3500 WKD 6500 410 490 900 1080 1800 2160 3000 3600 3500 3900 6500 7000 WKP 500 A KS 0.5 WKP 1000 A KS 0.5 WKP 2000 A KS 1.5 WKP 4000 A KS 1.5 WKP 4000 A KS 3.0 WKP 8000 KS 6.0 UNO 65 UNO 120 UNO 250 UNO 250 BA 501 BA 501 1 · 10-3 2 · 10-2 1 · 10-3 2 · 10-2 1 · 10-3 2 · 10-2 1 · 10-3 2 · 10-2 1 · 10-3 2 · 10-2 1 · 10-3 2 · 10-2 33 33 33 33 30 30 3.7 4.4 0.5 – 10 7 8 0.5 – 10 13 15 1.5 – 30 18.5 22.5 1.5 – 30 28.5 33.5 3 yes 62 40.5 48.5 6 yes 122 – 7.2 290 – 19 570 – 35 1230 – 35 1410 yes 50 2080 yes 66 4000 WOD 412 A WOD 900 A WOD 1800 A WOD 3000 A WOD 3500 A WOD 6500 A 410 490 900 1080 1800 2160 3000 3600 3500 3900 6500 7000 WKP 500 A WKP 1000 A WKP 2000 A WKP 4000 A WKP 4000 A WKP 8000 UNO 65 UNO 120 UNO 250 UNO 250 BA 501 BA 501 1 · 10-3 2 · 10-2 1 · 10-3 2 · 10-2 1 · 10-3 2 · 10-2 1 · 10-3 2 · 10-2 1 · 10-3 2 · 10-2 1 · 10-3 2 · 10-2 33 33 33 33 30 30 3.7 4.4 yes – – 7 8 yes – – 13 15 yes – – 18.5 22.5 yes 28.5 33.5 40.5 48.5 – yes 2 yes 2 – 7.2 250 – 19 530 – 35 980 – 35 1180 yes 50 1750 yes 66 3650 8.10.2 Series WOD-A WOD 222 A Volume flow rate at 10-1 mbar 50 Hz m3/h 220 60 Hz m3/h 265 Pumping station components Roots vacuum pumps WKP 250 A Single-stage rotary vane vacuum pumps UNO 35 Total pressure without gas ballast mbar 1 · 10-3 with gas ballast mbar 2 · 10-2 Water vapor compatibility mbar 33 Installed power output1) 50 Hz kW 1.85 60 Hz kW 2.2 Air cooling yes Water cooling – Cooling water requirement rpm – Cooling water monitor in backing pump – Oil filling, complete l 4.2 Weight kg 220 1) Depending on the operating condition, the power input may be reducted by as much as 70% 2) Inlet temperature max. 20 °C 60 8.10.3 Series WOD-B WOD 222 B Volume flow rate at 10-1 mbar 50 Hz m3/h 220 60 Hz m3/h 265 Pumping station components Roots vacuum pump WKP 250 A Two-stage rotary vane vacuum pump DUO 35 Total pressure without gas ballast mbar 1 · 10-4 with gas ballast mbar 1 · 10-4 Water vapor compatibility mbar 20 Installed power output1) 50 Hz kW 1.85 60 Hz kW 2.2 Air cooling yes Oil filling, complete l 4.2 Weight kg 220 WOD 412 B WOD 900 B WOD 1800 B WOD 3000 B 410 490 900 1080 1800 2160 3000 3600 WKP 500 A WKP 1000 A WKP 2000 A WKP 4000 A DUO 65 DUO 120 DUO 250 DUO 250 1 · 10-4 1 · 10-4 1 · 10-4 1 · 10-4 1 · 10-4 1 · 10-4 1 · 10-4 1 · 10-4 20 20 30 30 3.7 4.4 yes 5.7 250 7 8 yes 16 530 13 15 yes 28 980 18.5 22.5 yes 28 1180 1) Depending on the operating condition, the power input may be reducted by as much as 70%, 61 Technical formulas 9 Technical formulas 1 B 1333 (ps-pa) [mbar] pWo= –––– · ––––––––––––– S 1333 – ps Water vapor tolerance (DSP) 2 pD pv (pSD – pAD) pSD – pL B = –––– · –––––––––––––– + –––––––– [mbar] pv – pSD pv – pSD S · · · TGas Q1 Q2 Qn S = R · –––– · –– + ––– + ··· ––– [m3/h] Mn p M1 M2   Volume flow rate (pumping station) 5 · · kJ QW = QH2O · qH2O –– h [ ] Intake pressure (WKP/WGK)   p a S = Sth · 1 – –––v · ––– [m3/h] p Km Volume flow rate (WKP/WGK) 13 PV pv3 – p3 ––– =  2.5 → a =–––––––––– [mbar] p 0.963 · pv3 Fore-vacuum/intake pressure (WKP/WGK) Sv · (p + ∆p) S = –––––––––––– [m3/h] p 15 S ηvol = ––––– Sth Volumetric efficiency rate (WKP/WGK) ∆Thigh + ∆Tsmall Tm = ––––––––––––––– [k] 2 16 Km ηvol = –––––––––––––––– y S 1.5 Sth Km + ––– – –––v Sv Sth   Mean temperature differential (condenser) Volumetric efficiency rate (WKP/WGK) (TG in – TW out) – (TG out – TW in) [K] ∆ Tm = –––––––––––––––––––––––––––– TG in – TW out In –––––––––––– TG out – TW in 8 17 Mean temperature differential (heat exchanger) Conductance value (universal)  9  Sth · ∆p P = –––––––––––– [kW] 36000 ·  mech Power consumption (WKP/WGK) 62 Sv · pv p = –––––– [mbar] S Volume flow rate (WKP) Condensation heat (condenser) 7 11 14 · QW A = ––––– [m2] k · Tm Cooling surface (condenser) 6   12 TA – TB KB = FB –––––––––– TA – TF Mixed operating fluid in the liquid ring vacuum pump 4 Km S = Sth · ––––––––––––––– [m3/h] Sv 1.5 Sth Km +––– – ––– Sv Sth Volume flow rate (WKP/WGK) Tolerable inlet pressures for other vapors 3 10 —–––– 3.6 · r3 r · pm L = ––––– · (0.039 –––––– + 30 l η [m3/h] T √ ––) M 18 3.6 · r3 L = –––––– (2150 · r · pm + 95) [m3/h] l Conductance value (air at 20°C) 19 28 T Q1 Q2 V = R –– –– + –– + p M1 M2 ( r4 · pm L = 7750 ––––––– [m3/h] l Conductance value air (laminar flow range 20°C) (Gas)volume 20 29 r3 L = 340 ––– [m3/h] l Conductance value air (molecular flow range 20°C) 21 p1 . V1 = p2 . V2 Q3 ––– = [m3] …Mn ) at T = constant Boyle-Mariotte law 1 L = ––––––––––– [m3/h] 1 1 1 –– + –– + –– L1 L2 L3 Conductance value (in series) 22 L = L1 + L2 + L3...[m3/h] Conductance value (parallel) 23 1 L·S Seff = –––––– = ––––– [m3/h] 1 1 L+S –– + –– L S Volume flow rate (at the vacuum chamber) 24 S·p peff = ––––– [mbar] Seff Pressure (at the vacuum chamber) 25 V p1 t = –– In ––– [h] S p2 Pump down pressure (RPV/WKP/WGK) 26 V p1 + ∆p t = –– In –––––––– = [h] S p2 + ∆p Pump down pressure (WKP) 27 3.6 · qL Serf = ––––––– = [m3/h] p Required volume flow rate (leak rate) 63 Technical formulas Legend for the technical formulas A (m2) Cooling surface a (mbar) Partial pressure of the vapor-forming material in the atmospheric air pD (mbar) Vapor compatibility peff (mbar) Pressure at the end of the pipe pL (mbar) Permanent gas-partial pressure at the intake port p + peff (mbar) Mean pressure = ––––––– 2 Correction factor a 3 (m /h) Gas ballast volume (mbar) Set differential pressure on the overflow valve of the Roots vacuum pumps B ∆p ∆Thigh (K) Highest pressure differential ∆Tsmall (K) Smallest pressure differential η (Pa · s) Tenacity of the gas ηmech Mechanical efficiency rating of the pump (η ~ 0.85 for Roots vacuum pumps) ηvol FB (m3/h) ( Operating liquid current ) Heat transmission coefficient L (m3/h) Conductance value KB (m3/h) Fresh liquid requirement in combined operation Km l M P p p pm ps (mbar) Saturated vapor pressure of the pumped water vapor at operating temperature pSD (mbar) Saturation vapor pressure at the operating temperature of the pump pv (mbar) Fore-vacuum (counterpressure) p1 (mbar) (Starting/atmospheric) pressure (to equation 29) p2 (mbar) Pressure (in vacuum) pwo (mbar) Water vapor tolarance as per PNEUROP Volumetric efficiency rating kJ k –––––––––– h · m2 · K 64 pAD Maximum compression ratio of the Roots Vacuum Pump at pv · Q (kg/h) Material component throughput per hour Q (kg) Throughput of each component per flow rate · QH2O (––kgh–) · Qw (mbar) (to equation 11) Intake pressure of the Roots vacuum pump (––kJh– ) qH2O (––kg–) (mbar) (to equation 24) Pressure at the beginning of the pipe mbar qL –– –––––l s qpv S (cm) Pipe length (kg/kmol) Molar mass (kW) Power consumption/ motor power p (mbar) (Working) pressure pa (mbar) Water vapor partial pressure of the atmospheric air (value in practical operation pa = 13 mbar) ( kJ Water vapor volume to be condensed per hour Condensation heat/volume per hour Evaporation heat ) Total leak rate (of the system) ( Relationship of inflowing gas ballast quantity to the backing pump’s capability ) mbar · m3 R –––––––––– Universal gas constant kmol · K R = 83.14 r (cm) Pipe radius S (m3/h) Volume flow rate Seff (m3/h) Serf TS (°C) (m3/h) Required volume flow rate of the pumping station at the vacuum chamber Boiling temperature of the evacuated material under pressure on the exhaust ports of the pump TW in (K) Cooling water inlet temperature Sth (m3/h) Theoretical volume flow rate of the Roots vacuum pump TW out (K) Cooling water outlet temperature Sv (m3/h) Volume flow rate of the backing pump (at pressure pv) Tm (K) Mean temperature differential between gas and cooling T (K) Gas temperature TS (K) TA (°C) Temperature of the fed-back “revolving” operating liquid = emission temperature in the pump ports Boiling temperature under condensation pressure (in Example 1, page 22, TS = TS H2O) t (h) Pump down time V (m3) Operating temperature of the pump Volume of the vacuum chamber V (m3) Temperature of the fresh liquid of LRP (to equation 25) (Gas) volume V1 (m3) Volume of the gas with presuure p1 V2 (m3) Volume of the gas with presuure p2 TB TF TGas (°C) (°C) (K) Volume flow rate at the end of the line (vacuum chamber) Gas temperature TG out (K) Gas outlet temperature (K) Gas inlet temperature TG in 65 Technical formulas Notes ______________________________________ ______________________________________ ______________________________________ 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______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________ 67 Rough and medium vacuum Turbopumps Dry vacuum pumps Rotary vane vacuum pumps Roots vacuum pumps Diffusion vacuum pumps Leak detectors Valves Installation parts Technical modifications reserved. Ordering number: PW 0013 PE (December 2002) Vacuum gauges and control units Gas analysis Systems technology: Coating and Leak Detection systems Service Pfeiffer Vacuum · Headquarters/Germany Tel. +49-(0) 64 41-8 02-0 · Fax +49-(0) 64 41-8 02-2 02 · info@pfeiffer-vacuum.de · www.pfeiffer-vacuum.net