Teledyne 9110TH - Nitrogen Oxides Analyzer - Manual (Page 237)

Troubleshooting & Repair Model 9110TH NOx Analyzer
Teledyne Analytical Instruments 217
If the pump is operating but the unit reports a XXXX gas flow, do the following:
 Check for actual sample flow. To check the actual sample flow, disconnect
the sample tube from the sample inlet on the rear panel of the instrument.
Make sure that the unit is in basic SAMPLE mode. Place a finger over the
inlet and see if it gets sucked in by the vacuum or, more properly, use a flow
meter to measure the actual flow. If there is proper flow (see Table 10-3
for flow rates), contact Technical Support. If there is no flow or low flow,
continue with the next step.
 Check pressures. Check that the sample pressure is at or around 28 in-Hg-A
at sea level (adjust as necessary when in elevated location, the pressure
should be about 1” below ambient atmospheric pressure) and that the RCEL
pressure is below 10 in-Hg-A. The 9110TH/M will calculate a sample flow
up to about 14 in-Hg-A RCEL pressure but a good pump should always
provide less than 10 in.
 If both pressures are the same and around atmospheric pressure, the pump
does not operate properly or is not connected properly. The instrument does
not get any vacuum.
 If both pressures are about the same and low (probably under 10 in-Hg-A,
or ~20” on sample and 15” on vacuum), there is a cross-leak between
sample flow path and vacuum, most likely through the Perma Pure dryer
flow paths. See troubleshooting the Perma Pure dryer later in this Section.
 If the sample and vacuum pressures are around their nominal values (28 and
<10 in-Hg-A, respectively) and the flow still displays XXXX, carry out a
leak check as described in Section 7.5.
 If gas flows through the instrument during the above tests but goes to zero
or is low when it is connected to zero air or span gas, the flow problem is
not internal to the analyzer but likely caused by the gas source such as
calibrators/generators, empty gas tanks, clogged valves, regulators and gas
lines.
 If an Zero/Span valve option is installed in the instrument, press CALZ and
CALS. If the sample flow increases, suspect a bad Sample/Cal valve.
 If none of these suggestions help, carry out a detailed leak check of the
analyzer as described in Section 7.5.2.
7.2.3.2. Ozone Flow is Zero or Low
If there is zero or a low (<200 cm³/min) ozone flow, the unit displays an OZONE
FLOW WARNING message on the front panel and a value between 0.0 and 200
cm³/min for the actual ozone flow as measured by the internal mass flow meter. In this
case, carry out the following steps: