Sampling Pump; Pump Service Procedures - WatchGas NEO Service Manual

Service Manual
• First check the Raw Zero readings. If these are significantly 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.
PID
NEO PPM MP181 Ch 1
Ch 2
Ch 1
Ch 2
NEO BENZ MP186 Ch 1
Ch 2
Ch 1
Ch 2
*These values are typical for a new instrument and are not to be construed as hard specifications.

2.2 SAMPLING PUMP

The flow 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 significantly lower flow. Also, if excessive dust or particles enter the
pump, the flow will be reduced. A strong pump should stall and/or nearly stop when a finger is used to
block the inlet. If the pump does not stall but the flow 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.

2.2.1 Pump Service Procedures

1. Check for a dirty or plugged filter by removing the inlet 25-mm fil-
ter and re-measuring the flow rate. Replace as needed.
2. Place a finger 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 flow 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 Configuration Mode (see NEO
User Guide). Briefly block the inlet probe with a finger and observe
Photoionization Detector NEO
10.6 eV 10.6 eV
Test Gas Raw Zero
10 ppm IBE 61000±1000
10 ppm IBE 61400±300
100 ppm IBE 61000±1000
100 ppm IBE 61400±300
9.8 eV
Test Gas Raw Zero
10 ppm IBE 61000±1000
10 ppm IBE 61400±300
100 ppm IBE 61000±1000
100 ppm IBE 61400±300
7
10.6 eV
Raw Span
≤50000
≤61100
≤500
≤60000
9.8 eV 9.8 eV
Raw Span
≤11000
≤60500
≤100
≤52000
D e t e c t i o n D e t e c t i o n
10.6 eV
Delta
≥9000
≥200
≥60000
≥1000
9.8 eV
Delta
≥50000
≥900
≥60000
≥9000
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