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7
Detection
Service Manual Photoionization Detector NEO
D e t e c t i on
10.6 eV 10.6 eV 10.6 eV 10.6 eV
PID Test Gas Raw Zero Raw Span Delta
NEO PPM MP181 Ch 1 10 ppm IBE 61000±1000 ≤50000 ≥9000
Ch 2 10 ppm IBE 61400±300 ≤61100 ≥200
Ch 1 100 ppm IBE 61000±1000 ≤500 ≥60000
Ch 2 100 ppm IBE 61400±300 ≤60000 ≥1000
9.8 eV 9.8 eV 9.8 eV 9.8 eV
Test Gas Raw Zero Raw Span Delta
NEO BENZ MP186 Ch 1 10 ppm IBE 61000±1000 ≤11000 ≥50000
Ch 2 10 ppm IBE 61400±300 ≤60500 ≥900
Ch 1 100 ppm IBE 61000±1000 ≤100 ≥60000
Ch 2 100 ppm IBE 61400±300 ≤52000 ≥9000
• First check the Raw Zero readings. If these are signicantly outside the ranges listed below, there is
probably something wrong with the sensor or circuit board.
• Apply calibration gas to the instrument. The readings should decrease by approximately the Delta
values listed below, for a new lamp. There is no set limit to the minimum Delta decrease, but com-
monly if the Delta is only 1/3 these values, the lamp is getting weak, and if it is 1/10th these values,
it is likely time to replace the lamp.
*These values are typical for a new instrument and are not to be construed as hard specications.
2.2 SAMPLING PUMP
2.2.1 Pump Service Procedures
The ow rate should be roughly 250-350 cc/min at low pump speed and 350-450 cc/min at high pump
speed when there is no air leakage. When approaching the end of its useful operating life, the pump
will consume more energy and draw signicantly lower ow. Also, if excessive dust or particles enter the
pump, the ow will be reduced. A strong pump should stall and/or nearly stop when a nger is used to
block the inlet. If the pump does not stall but the ow is weak, it is likely that particles are trapped in the
pump gasket or diaphragm. When this occurs, it is necessary to replace or rebuild the pump, or clean the
gasket. Repair of the pump requires removal of the circuit board and should be done by an authorized
service center.
1. Check for a dirty or plugged lter by removing the inlet 25-mm l-
ter and re-measuring the ow rate. Replace as needed.
2. Place a nger over the probe inlet and listen for a strain on the
pump. It should nearly stop, but may not stop completely. If the
pump tone barely changes, check the ow path, such as the inlet
probe Luer connector and sensor cap.
NOTE: The sensor cap should be screwed down only hand tight to
avoid damage to the sensor grid and possibly lamp. Typically the
green O-ring should be partially visible.
3. Check the Pump stall threshold in Conguration Mode (see NEO
User Guide). Briey block the inlet probe with a nger and observe
