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HGM-MZ Sample pump flow testing
This procedure describes the correct method for testing the sampling pump in order to
determine its proper sample flow and vacuum.
HGM-MZ Pump Testing;
If the HGM- MZ is unable to pull a vacuum it will generally be due to one of two things, either the
pump is not running or failed, or there is a leak in a valve or valve stuck open in the manifold.
Flow detection is based on a minimum drop from ambient pressure and a minimum value above
vacuum, so a vacuum failure will generally result in a NO flow indication on all zones.
The pinch test can isolate the problem quickly. In the diagnostic screen observe the live
pressure "PRES", then pinch the tube on one side of the white disc (Hydrophobic filter) pinching
either side is OK. This will dead head the pump, a good pump will drop the pressure to
approximately 3 psia below the Ambient reading. If you get no change, the pump is not
working, the “EXHAUST” port is restricted, or there is a leak between the pinch point and the
pump.
If the pinch yields a good vacuum number, the problem is before the pinch in the valve
manifolds. One or more manifold valves are either stuck open or a failed valve driver board is
electrically holding it open. (See separate tech Bulletin on Manifold testing procedure)
Pump Vacuum (VAC)
Ambient Air Pressure (AMB)
Indicates good or bad pump
Enter Diagnostic Screen (DIAG)
From SETUP Screen
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