Teledyne 9110TH - Nitrogen Oxides Analyzer - Manual (Page 211)

Instrument Maintenance Model 9110TH NOx Analyzer
Teledyne Analytical Instruments 191
6.3. PREDICTIVE DIAGNOSTICS
The analyzer’s test functions can be used to predict failures by looking at trends in their
values. Initially it may be useful to compare the state of these test functions to the
values measured on your instrument at the factory and recorded on the 9110TH/M Final
Test and Validation Data Form (TAI part number 04490, attached to the manual). Table
6-2 can be used as a basis for taking action as these values change with time. The
internal data acquisition system (DAS) is a convenient way to record and track these
changes. APICOM control software can be used to download and review these data
even from remote locations (Section 4.15.2.8 describes APICOM).
Table 6-2: Predictive Uses for Test Functions
FUNCTION EXPECTED ACTUAL INTERPRETATION & ACTION
RCEL
pressure
Constant to
within ± 0.5
Fluctuating Developing leak in pneumatic system. Check for leaks
Slowly increasing
Pump performance is degrading. Replace pump head
when pressure is above 10 in-Hg-A
SAMPLE
pressure
Constant within
atmospheric
changes
Fluctuating Developing leak in pneumatic system. Check for leaks
Slowly decreasing Flow path is clogging up. Replace orifice filters
Slowly increasing
Developing leak in pneumatic system to vacuum
(developing valve failure). Check for leaks
Ozone Flow
Constant to
within ± 15
Slowly decreasing Flow path is clogging up. Replace orifice filters
AZERO
Constant within
±20 of check-out
value
Significantly
increasing
Developing AZERO valve failure. Replace valve
PMT cooler failure. Check cooler, circuit, and power
supplies
Developing light leak. Leak check.
O
3
air filter cartridge is exhausted. Change chemical
NO2 CONC
Constant for
constant
concentrations
Slowly decreasing
signal for same
concentration
Converter efficiency may be degrading. Replace
converter.
NO CONC
Constant for
constant
concentration
Decreasing over time
Drift of instrument response; clean RCEL window,
change O
3
air filter chemical.
6.4. MAINTENANCE PROCEDURES
The following procedures need to be performed regularly as part of the standard
maintenance of the Model 9110TH/M.
6.4.1. CHANGING THE SAMPLE PARTICULATE FILTER
The particulate filter should be inspected often for signs of plugging or excess dirt. It
should be replaced according to the service interval in Table 9-1 even without obvious
signs of dirt. Filters with 1 µm pore size can clog up while retaining a clean look. We
recommend to handle the filter and the wetted surfaces of the filter housing with gloves