美国Televac 4A真空计

• Convection Gauge Tube (1 mTorr - 1.000 Torr)
• Rugged sensor housing of stainless steel withstanding 150 psioverpressure
• Less than 500 milliseconds response time for a pressure changefrom 10^-5 Torr to atmosphere
• Calibration medium of dry air or nitrogen
• Optional display (1-1,000 microns)
• Adjustable set point with LED indicator

The convection gauge measures absolute pressures by determining theheat loss from a fine wire filament maintained at a constanttemperature. The response of the sensor depends on the gas type. Apair of thermocouples are mounted at a fixed distance from eachother. One thermocouple is heated to a constant temperature by avariable current power supply. Power is pulsed and the temperatureis measured between heating pulses. The second thermocouplemeasures convection effects and also compensates for ambienttemperature. This sensor must be mounted vertically.