Preventive Maintenance
Flame photometric detector
NOTE: Once installed, the ferrule cannot be removed from the liner for reuse unless both parts are still warm.
Cleaning/replacing the FPD jet
If a response problem is encountered (sensitivity, noise, selectivity), the FPD jet should be inspected for deposits and, if necessary, cleaned or replaced. To service the jet properly, the detector module should be removed from the instrument, followed by appropriate service:
1.Turn off power to the gas chromatograph and disconnect the main power cord. Remove the detector covers.
2.Turn off hydrogen, air (or oxygen) and auxiliary nitrogen supplies to the detector (manifold on/off valves). For convenience, carrier flow may be left on. Allow time for heated zones to cool to safe temperatures.
3.Remove the photomultiplier tube (PMT) assembly from the detector module; also remove the filter. Set both in a safe place. Also, remove exhaust tubing (1/4•inchswage fitting) and the chimney assembly (two M4 screws on sides). Then loosen the U clamp that locks the burner to support bracket (Part No. 19256•00080),and disconnect the jet assembly from the transfer line tube. Carefully lift the detector module vertically from the transfer tube so as not to damage the fused silica liner. See Caution and WARNING notes which follow.
Note: It is unnecessary to disconnect any plumbing, ignitor leads, or the heater/sensor. Leave all attached and disconnect the detector block from the transfer line at the 1/4•inchswage fitting; then gently lift block and rotate it enough to access the jet.
4.Remove and inspect the jet assembly. Use a suitable wire to remove any deposits.
5.This is also an ideal time to inspect/clean the glow plug (see Flame ignition problems) and inspect/clean the quartz windows (see Cleaning/replacing windows, filter, seals).
197