Inficon TPG300 - 5 Adjustment; Adjusting the Pirani Measurement Circuit

12 IG9972BEN (2017-09) Plug-In Boards.om
5 Adjustment
Pirani measurement circuits are factory-adjusted to the standard gauge. Due to
manufacturing tolerances, contamination of the gauges, and different cable
lengths, deviations are inevitable.
Cold cathode measurement circuits are factory-adjusted and require no readjust-
ment.
Two trimmer potentiometers are available for compen-
sating the gauge tolerances, gauge contamination, or
different cable lengths, within certain limits.
The adjustment should only be performed
after the equipment has attained operating
temperature (≈10 minutes).
• With gauge connected, lower the vacuum chamber pressure to <1×10
-4
hPa
• Select the measurement circuit to be adjusted (»sensor« mode)
• With the <HIGH VAC> potentiometer adjust the display to 8.0×10
-4
hPa
• Turn the potentiometer clockwise by 90°
• «ur 10
-4
» should now be displayed (→  [1]).
• Expose the gauge to atmospheric pressure (vent the vacuum chamber)
• Turn the <ATM> potentiometer to obtain a reading of 1.0×10
3
hPa
• Decrease the pressure to <1×10
-4
hPa
• Check the high vacuum reading and readjust, if necessary.
5.1 Adjusting the Pirani
Measurement Circuit
Adjustment at High Vacuum
Adjustment at Atmospheric
Pressure