NOA Gas Sampling Problems

A list of possible problems with the chemiluminescence detector appears below. If the problem is not listed below or assistance is needed, contact GE Analytical Instruments.

Gas calibration outside recommended limits
Possible Causes Action Required
NO gas concentration low due to absorption in regulator Allow cal gas to flow for at least 5 minutes before calibrating.
Cal gas flow rate too low(no flow out open leg of tee) Increase cal gas flow rate to > 250 mL/min.
Dirty/clogged frit restrictor Clean or replace the frit restrictor.
Dirty filter Replace Teflon filter in gas sampling line.
Dirty reaction chamber Clean reaction chamber.
High voltage needs adjustment Contact GE Analytical Instruments.

Zero air calibration outside recommended limits
Possible Causes Action Required
Leak at zero air filter Confirm all connections are tight.
No flow through zero air filter Ensure caps are removed from both ends of zero air filter.
Light leak See PMT test in Detector Problems troubleshooting section.
Cooler temperature too high Allow at least 30 minutes after turning power on before calibrating.
Perform cooler maintenance if necessary.

High background after NO calibration
Possible Causes Action Required
Dirty Teflon filter Replace the filter.