GE MOA 280i, Руководство по эксплуатации и обслуживанию

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GE Analytical Instruments ©2006
16-12
DLM 14291 Rev. A
Lower than expected NO concentration can occur if the NO calibration gas is past
its expiration date and for new NO cylinders and regulators. Try letting the NO
calibration gas flow for 10-15 minutes and repeat the calibration.
In some cases it may be necessary to adjust the high voltage for the PMT to
achieve in-range calibrations. Contact Sievers for assistance.
High Background NO after Calibration
After calibration, the NOA’s signal should return to the background levels within 5
to 10 minutes. If something in the gas sampling package has absorbed NO, a high
background will be observed and a loner time required to return to the background
levels. The most common problem is a dirty Teflon filter. Try replacing the filter
and see if this solves the problem.
Liquid Measurements Problems
The most common problems observed in liquid measurements are low sensitivity
and poor repeatability. Both of these problems can be caused by leaks in the purge
system, a dirty reaction chamber or dirty purge vessel and problems with the
syringes used for injection of the samples.
Low Sensitivity
Reduced sensitivity can be cause by:
•
A dirty reaction chamber ((see Cleaning the Chemiluminescence Reaction Cell,
page15-5).
•
Clogged frit restrictor (see Testing and Cleaning the Flow Restrictor Frit, page
15-13).
•
Leaks in the purge system.
•
Water bath not at >90 °C (nitrate only)
•
Depleted reagents.