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ACM 150
Manual tests and evaluations
Pneumatic tests
The pneumatic tests identify problems with the sampling system, including the
pumps, valves, filters and tube fittings. Problems identified include:
•
interruption of sample flow
•
restriction of sample flow
•
cross-stream leaks
•
outside air leaks
Cycle valve tests
If you are at the monitor, refer to
location, refer to
transducer ('sample pressure' or 'sample cell') as the ACM 150 monitor scans
through all of its active points.
If you are using the long path gas cell, you should see the pressure changing in
accordance with (or readings you have recorded for your specific monitor). Identify
problems as follows:
•
Fails to Draw a Vacuum: This indicates that either the Gas Cell Venturi Pump
or the Back-up Exhaust Pump (if used) is not drawing a vacuum and needs
servicing or that valve S6 is failing to open, S2 is stuck open or leaking or a leak
has developed in the gas cell or its connections.
•
Draws Vacuum but Vacuum Remains - All Points: If the pressure fails to rise
during the Surge or Fill cycles all of the time, S6 is stuck open or leaking, S2 is
failing to open or the Boost Pump has failed.
•
Draws Vacuum but Vacuum Remains - Specific Sample Point: If the pressure fails
to rise during the Surge or Fill cycles for any specific sample point, the valve for
that point is failing to open.
•
Slowly Returns to 0 During Fill Cycle - Specific Sample Point: This indicates a
flow restriction. Most likely, the in-line filter on that point needs to be replaced. To
make sure the problem is not inside the ACM 150 monitor, disconnect the sample
tube(s) from the problem point(s). If you observe that the Fill Cycle goes to 0 psig
in 1-2 seconds with the line disconnected, assume the restriction is at the in-line
filter or the sample tubing (or the check valve if the line leak option is used). If
disconnecting the tube makes no difference, the flow restriction is in the sample
valve for that point or in one of the 10–port manifolds.
•
Slowly Returns to 0 During Fill Cycle - All Points: This indicates an internal flow
restriction. The gas cell filter needs changing or the Boost Pump needs servicing.
To confirm problems with the Cycle Valves, test the valves using ACM Manual
Control,
Figure
valves on and off observing the changes to the gas cell pressure readings. Service
cycle valves following
Cycle valve control
View valve
cycles. Observe the readings from the gas cell pressure
73, via the computer or use the Frontpanel Mode. Selectively turn
Servicing the cycle
panel, or if you are at a remote
valves.
126
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