Panametrics CGA 351, User Manual, Page: 83 / 119

CGA 351 User’s Manual 77
Chapter 5.
Check for Plumbing Leaks
A plumbing leak permits contamination of the reference air by the sample gas. The resulting reduction in the ratio of
the oxygen partial pressures reduces the mV output from the oxygen sensor and yields a percent oxygen reading
that is higher than expected. Use the following steps to remedy the problem:
1. Open the sensor enclosure cover to allow uncontaminated reference air to enter the unit.
2. If the oxygen reading drops in Step 1 above, tighten all fittings by 1/8 turn and close the sensor enclosure cover. If
the oxygen reading gradually increases, repeat Step 1. If the problem persists, proceed to the next section.
CAUTION!
Do not tighten fittings more than 1/8 turn at a time.
Check the Oxygen Sensor Temperature
If the oxygen sensor is below its normal operating temperature, the mV output will be too low and the percent oxygen
reading will be higher than expected. Proceed as follows:
•
The easiest way to check the sensor temperature is to calibrate the oxygen sensor as described in “Calibrating
the CGA 351” on page 62. The calibration procedure includes instructions for adjusting the sensor furnace
temperature, if necessary.
If the problem has not been resolved by the steps in this section, contact the factory for assistance.