Teledyne 9110T Replacing Critical Flow Orifices, To clean or replace a critical flow orifice

Model 9110T NOx Analyzer Instrument Maintenance

∙If tests show that cleaning is necessary, refer to Section 11.3.10 on how to clean the critical flow orifice.

8.Do not remove the sample and ozone nozzles. They are Teflon threaded and require a special tool for reassembly. If necessary, the manifold with nozzles attached can be cleaned in an ultrasonic bath.

9.Reassemble in proper order and re-attach the reaction cell to the sensor housing. Reconnect pneumatics and heater connections, then re-attach the pneumatic sensor assembly and the cleaning procedure is complete.

10.After cleaning the reaction cell, it is also recommended to exchange the ozone supply air filter chemical as described in Section 11.3.3.

11.After cleaning, the analyzer span response may drop 10 - 15% in the first 10 days as the reaction cell window conditions. This is normal and does not require another cleaning.

11.3.10.REPLACING CRITICAL FLOW ORIFICES

There are several critical flow orifices installed in the 9110T (see Figure 13-9 for a pneumatic location of each orifice). Despite the fact that these flow restrictors are protected by sintered stainless steel filters, they can, on occasion, clog up, particularly if the instrument is operated without sample filter or in an environment with very fine, sub-micron particle-size dust.

Figure 11-7: Critical Flow Orifice Assembly

To clean or replace a critical flow orifice:

Teledyne Analytical Instruments 256