Instruction Manual VGC301 Controller
InstruTech, Inc.
Page 38
9
Service
9.1
Calibration
Every InstruTech CVG101 sensor is calibrated prior to shipment using nitrogen (N
2
). However, you can calibrate the
instrument by adjusting zero and span (atmosphere) using the procedure described previo
usly in section 4.2 titled
“Programming”.
Zero and span (atmosphere) calibration affect the displayed value and the output signal. Zero calibration
optimizes performance of the gauge when operating at a low pressure range of 1 x 10
-4
Torr to 1 x 10
-3
Torr. If your
minimum operating pressure is higher than 1 x 10
-3
Torr, it is not normally necessary to perform calibration at zero and thus
span calibration should be adequate. If you are able to evacuate your system to below 1 x 10
-4
Torr, it is always a good
practice to check and set zero if necessary. This will also improve performance in cases where gauge contamination is
causing higher readings than 1 x 10
-4
Torr even though the system has been evacuated to below 1 x 10
-4
Torr. Care should
be exercised when using gases other than nitrogen (N
2
) / air.
9.2
Maintenance
In general, maintenance is not required for your InstruTech sensor and controller. Periodic performance checks may be
done by comparing the sensor to a known reference standard.
9.3
Troubleshooting
Indication
Possible Cause
Possible Solution
Display is off / blank
No power
Check power supply & power cable
Readings appear very different from
expected pressure
The process gas is different from the gas
used to calibrate the CVG101 gauge
Correct readings for different gas thermal
conductivity. See
section 5
on using the gauge with
different gases
CVG101 gauge has not been calibrated
or has been calibrated incorrectly
Check that zero and span are adjusted correctly
Readings are noisy or erratic
Loose cables or connections
Check and tighten connections
Contamination
Inspect the CVG101 for signs of contamination
such as particles, deposits, discoloration on gauge
inlet. Return to factory for possible cleaning
Vibration
Ensure gauge is not mounted where excessive
vibration is present
Gauge cannot be calibrated - zero and
span can’t be adjusted
Contamination
Sensor failure for other cause
Return the CVG101 to factory for possible cleaning
Replace the CVG101
Setpoint does not actuate
Incorrect setup
Check setpoint setup
Display shows “Sensor Bad”
Sensor wire damaged
Replace the CVG101
Display shows “overpressure”
System pressure over 1000 Torr
Faulty electronics
Reduce pressure
Repair or replace the VGC301 electronics
Atmospheric pressure reads too high
and can’t be set to correct value
Contamination
Sensor wire damaged
Return the CVG101 to factory for possible cleaning
Replace the CVG101
Atmospheric pressure reads too low
and can’t be set to correct value
Sensor wire damaged
Contamination
Replace the CVG101
Return the CVG101 to factory for possible cleaning
