Agilent Technologies FRG-700 User Manual page 30

Technical Information
Gas type dependence
Ignition delay
As long as the cold cathode measuring circuit has not yet ignited, the measured
value of the Pirani is output as measuring signal. The status output (pin 6, low)
indicates the Pirani-only mode.
If the gauge is activated at a pressure p < 3×10
NOTE
whether the cold cathode system has ignited.
Once flanged on, permanently leave the gauge in the operating mode irrespective of
NOTE
the pressure range. Like this, the ignition delay of the cold cathode measuring
circuit is always negligible (<1 s), and thermal stabilizing effects are minimized.
30 Agilent Inverted Magnetron Pirani Gauge FRG-700 and FRG-702 User Manual
The measuring signal depends on the type of gas
being measured. The curves are accurate for dry
air, O , CO and N . They can be mathematically
2 2
converted for other gases.
If you are using an Agilent controller, you can
enter a calibration factor to correct the pressure
reading.
When cold cathode measuring systems are
activated, an ignition delay occurs. The delay time
increases at low pressures and is typically:
-5
10 mbar 1 second
≈
10 -7 mbar 20 seconds
≈
5×10 -9 mbar 2 minutes
≈
-9
, the gauge cannot recognize