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Total Pressure Measurement Total Pressure Measurement Vacuum Sensors Display and control unit 5 Accessories Contents Introduction Page 5-3 to 5-6 Hot Cathode Ionization Vacuum Sensorss Page 5-7 to 5-14 Cold Cathode Ionization Vacuum Sensors Page 5-15 to 5-17 Heat Loss Vacuum Sensors Page 5-18 to 5-25 Capacitance Diaphragm Sensors Page 5-26 to 5-30 Relative Pressure Sensors Page 5-31 to 5-33 5 Display and Control Units Page 5-34 to 5-39 Contamination Protection Page 5-39 Cables Page 5-40 to 5-41 5-2 www.vacom-vacuum.com Total Pressure Measurement Introduction For all types of vacuum applications VACOM offers reliable total pressure sensors covering a wide pressure range from atmosphere to XHV. This catalogue introduces VACOM’s own, technologically leading products that can be used out-of-the-box or adapted in a customer specific version. The following chapter provides an overview of VACOM-selected sensors for total pressure measurement as well as suitable controllers. Used to determine the absolute pressure in almost every application. For more detailed information about vacuum gauges please do not hesitate to contact our technical support team. Measuring Principles for Total Pressure Instruments and Typical Measurement Ranges Extreme/Ultra high vacuum High vacuum Medium/Rough vacuum Bourdon 5 Heat loss (Pirani, Thermocouple) Membrane (capacitance, piezo) Wide range (ionization and heat loss) Ionization (Hot Cathode Ionization, Cold Cathode Ionization) Custom made (ionization, heat loss) 10-12 10-10 10-8 10-6 10-4 10-2 100 102 mbar Pressure Units 1 Pa = 0.01 mbar = 0.0075 Torr 1 micron = 1 mTorr = 0.133 Pa = 1.33E-3 mbar 1 mbar = 100 Pa = 1 hPa = 0.75 Torr 1 psi = 6895 Pa = 69 mbar = 51.7 Torr 1 Torr = 1 mmHg = 133 Pa = 1.33 mbar 1 atm = 760 Torr = 1013 hPa = 1013 mbar = 14.7 psi Vacuum Pressure Ranges Pressure range Absolut pressure in mbar Molecules per cm3 Mean free path Atmosphere 1013 2,7 · 10-19 68 nm Rough Vacuum 1013 …1 1019 … 1016 0,1 … 100 µm Medium Vacuum 1 … 10-3 1016 … 1013 0,1 … 100 mm High Vacuum (HV) 10-3 … 10-7 1013 … 109 0,1 … 1000 m Ultra high Vacuum (UHV) 10-7 … 10-11 109 … 105 1 km … 104 km Extreme Ultra high Vacuum (XHV) < 10-11 < 105 > 104 km www.vacom-vacuum.com 5-3 Total Pressure Measurement Selection Criteria for Vacuum Gauges Measurement Measurement Measurement Measurement range accuracy conditions results Measurement Reproducibility Process media Display principles Response time Process environment Process control Bakeout capability Signal transmission 5 Measurement range Which method offers an appropriate measurement range? Is one single method sufficient or is it necessary to combine different methods? Are combination gauges suitable? Accuracy, reproducibility, and response time What accuracy does the vacuum application require? Which method offers a sufficient precision? Which reproducibility and response time of the sensor is necessary? Composition of the measured process media Are correction factors for gas-type dependent measurements relevant/known? Is the gas composition variable? Process and environmental conditions Which gases and conditions is the sensor exposed to? (Gas: corrosive, hazardous, oxidizing/reductive, etc.; Conditions: contaminated areas, particle-rich environment, low/high temperatu- res, high voltages, strong magnetic fields, electric discharges, fast pressure rise or surge pressures, etc.) Is a protection of the inlet port necessary, by means of a baffle, a valve, a bent tube etc.? Which other requirements must the sensor of choice meet? (Protection against contaminants and water; mechanical strength; climatic and geographical conditions; ionizing radiation; etc.) Is the examined gas mixture flammable? Are explosion-proof gauges required? Bakeout capability What temperature limit is required for the gauge and the cable? Need temperature sensitive parts to be removable? Do temperature sensitive parts need to bee removable? Display Is a pressure display required? If yes, is a an active sensor with integrated display useful or is a separate display unit needed? Process control, data logging What type of communication interface (analog, RS232, profibus, …) is needed? How many setpoints are necessary? Signal transmission Which type of signal (analog/digital) needs to be transmitted over which cable length and in which quality? 5-4 www.vacom-vacuum.com Total Pressure Measurement Order information and compatibilities Order code example: BARION - EXTENDED - S - 0 - CF40 Product range - Product type - Characteristic - Interface2 - Size of flange BASICII, PROII, S 0 CF40 EXTENDED BARION CF40, CF16, KF16, ATMII, HV S,E,C 0, A3 KF25 VaX linkB E A3 4 VaX S1S2S3 E SBU35 BASIC, PRO, COLDION S 0 CF40 EXTENDED 5 KF16, NPT18, ANYGAS BASIC C 0 NPT14 RFM CU or 316 S 0, A KF16, G14 NPN5V or PNPV, SWITCH NPN20MA or C A SL14, VCR,14 PNP20MA CF16R, KF16, MEMBRAN 10TORR25 C A3 12, VCR8 KF25, KF16, THERM 20 or 1 S 0 NPT18 KF16, KF25, PIRANI SDM3 or 000 C 0, A, 3A NPT18, 12 COLD P C A CF40, KF40, KF25 1 S: Sensors | E: Electronics | C: Complete 2 0: none | R: RS232 | 3A: Analog + RS232 | A: Analog 3 SDM= Setpoint (S: yes, 0: no) | Display (D: yes, 0: no) | Membrane (M: yes, 0: no) 4 S1: Slot 1 (0, A or H) | S2: Slot 2 (0, A or H) | S3: Slot 3 (0, A or H) A: Active module | H: Hot cathode sensor module | 0: free Module area Control units - Product range - - Sensors1 - Examples - Length Old name Examples CABLE VAX BARIONBPS 3M, 5M, 10M, 15M CABLE VAX BARIONBPE 3M, 5M, 10M, 15M CABLE MVC3 BARIONBPE 3M, 5M, 10M, 15M BATL, BSL CABLE VAX LAH 3M, 5M, 10M, 15M CABLE VMG LAH 3M, 5M, 10M, 15M CABLE VAX ANYGAS 3M, 5M, 10M, 15M CABLE VMG ANYGAS 3M, 5M, 10M, 15M CABLE VAX PIRANISD0 3M, 5M, 10M, 15M SSL CABLE VMG PIRANISD0 3M, 5M, 10M, 15M SSL+Adapter CABLE VAX PIRANIS00 3M, 5M, 10M, 15M LSL CABLE VMG PIRANIS00 3M, 5M, 10M, 15M LSL+Adapter CABLE VAX MEMBRAN 3M, 5M, 10M, 15M CSL CABLE VMG MEMBRAN 3M, 5M, 10M, 15M CSL+Adapter CABLE VAX COLD 3M, 5M, 10M, 15M LSL CABLE VMG COLD 3M, 5M, 10M, 15M LSL+Adapter CABLE PIRANIC PIRANI000 3M, 5M, 10M, 15M CB421 1 BARIONBPS: BARION basic II, BARION pro II, BARION smart(F) PIRANISD0: Pirani sensors of the type SD0 BARIONBPE: BARION basic, pro, extended PIRANIS00: Piranisen sensors of the type S00 LAH: BARION atm(II), BARION HV, VaX linkB MEMBRAN: Diaphragm sensors ANYGAS: Anygas COLD: Cold PIRANI000: Pirani sensors of the type 000 www.vacom-vacuum.com 5-5 Total Pressure Measurement Selection Criteria for Vacuum Gauges In general, it is essential to decide if an active (also called transmitter) or a passive one should be used. The transmitter is a gauge with integrated measuring and control electronics. It provides standardized analog voltage (e.g. 0…10 V), current (e.g. 4…20 mA) or digital output signals (e.g., via RS232, Profibus DP). BARION® atm II is one example of transmitters. A passive gauge consists only of one sensor head. The power supply and data processing is provided by an external controller. The advantage of using a passive sensor is the possibility to use higher operating temperatures in applications, where bake-outs cannot be avoided. BARION® pro II is an example of the passive gauge. An exact definition of the measured value is important since most gauges measure the absolute pressure. These sensor suit well in applications and processes dependent on the ambient pressure such as valves opening only when there is no pressure gradient. Total pressure instruments – Made by VACOM® As our partners you can benefit from our long-term experience. Our well established product line is distinguished through its high accu- racy, robustness, safety, quality, and long life-time as well as through its user-friendliness in various industrial and research processes. 5 We are happy to customize our devices according to your specific requirements. 5-6 www.vacom-vacuum.com Product Overview To facilitate your search for the right vacuum gauge, the sensors in this chapter are arranged according to their measurement principle. Each sensor group is introduced with a small description of the physical processes that are used for the pressure determination. Compatibility Measurement range (10n mbar / 10n+2 Pa / 10n Torr) Control units Sensors n= -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 VMG CU-100 VaX linkB VaX VaX Vacuum Explorer Vacuum VaX BARION® basic II P BARION® pro II P 5 BARION® P extended BARION® smart P BARION® smartF P BARION® move P BARION® atm II A BARION® HV A COLDION® basic A COLDION® pro A COLDION® A extended COLD A RFM M SWITCH A ANYGAS A MEMBRAN* A PIRANI A THERM P (Thermocouple) * Membrane: There are different device version with 3/4 pressure decade reliable. www.vacom-vacuum.com 5-7 Hot Cathode Ionization Vacuum Gauges Measurement Principle With decreasing absolute pressure levels it is difficult to measure the pressure as force per area unit. The force differences become so small that they are no longer resolvable. A very practical but indirect method of measuring high vacuum is the "counting" of gas particles. Thus, the particle number density n (gas density) is determined, which is proportional to the gas pressure p according to the relation p=nkT. The idea is to ionize the gas, since ions can be easily detected with a collector electrode. Therefore, electrons are accelerated to cause collision ionizations. This is possible in a wide pressure range from medium up to extreme high vacuum, where the particles have a sufficiently high mean free path.
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