Teledyne 9110EH - Nitrogen Oxides Analyzer - Manual (Page 215)

Model 9110EH Instruction Manual Troubleshooting & Repair
• 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 11.5.2
• 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 IZS or 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 11.5.2.
11.2.1.2. Ozone Flow is Zero or Low
If there is zero or a low (<50 cm³/min) ozone flow, the unit displays an OZONE FLOW
WARNING message on the front panel and a value between 0.0 and 50 cm³/min for the
actual ozone flow as measured by the internal mass flow meter. In this case, carry out the
following steps:
• Check the actual flow rate through the ozone dryer by using an external flow meter
to the inlet port of the dryer. This inlet port is inside the analyzer at the end of the
plastic particle filter (Section 9.3.2 for illustration). If there is nominal flow (about
140 cm³/min from 80 cm³/min O
3
flow and 60 cm³/min purge flow), consult
customer service as there is a problem with the firmware or electronics.
• If the actual flow is low or zero, check if the pump operates properly. The RCEL
pressure should be below 10 in-Hg-A at sea level. If it is above 10”, rebuild the
pump (Section 9.3.4). Check the spare parts list in Appendix B on how to order
pump rebuild kits.
• Check if the particle filter is clogged. Briefly remove the particle filter to see if this
improves the flow. Be very cautious about handling the Perma Pure dryer fittings -
refer to Section 9.3.2 on proper handling instructions. If the filter is clogged, replace
it with a new unit. If taking off this filter does not solve the problem, continue to the
next step. Do not leave the Perma Pure dryer without filter for more than a few
seconds, as you may draw in dust, which will reduce the performance of the dryer.
• A leak between the flow meter and the reaction cell (where the flow-determining
critical orifice is located) may cause a low flow (the system draws in ambient air
through a leak after the flow meter). Check for leaks as described in Section 11.5.1.
Repair the leaking fitting, line or valve and re-check.
• The most likely cause for zero or low ozone flow is a clogged critical flow orifice or
sintered filter within the orifice assembly. The orifice that sets the ozone flow is
located on the reaction cell. Check the actual ozone flow by disconnecting the tube
from the reaction cell and measuring the flow going into the cell. If this flow is
correct (~80 cm³/min), the orifice works properly. If this flow is low, replace or
clean the orifice. The orifice holder assembly allows a quick and easy replacement of
the orifice, refer to Section 9.3.10 on how to do this. Appendix B lists a spare part kit
with a complete orifice assembly that allows a quick replacement with minimum
instrument down-time. The clogged orifice can then be cleaned while the instrument
is running with the replacement.
M9110EH Rev 0 201