Troubleshooting with the Backpressure Gauge

Document ID

Document ID TE6605

Version

Version 3.0

Status

Status Published

Published Date

Published Date 21/01/2019
Question
Troubleshooting with the Backpressure Gauge
Summary
Troubleshooting with the Backpressure Gauge
Answer
Since approximately April 1999, APA6000 colorimetric analysers have been equipped with a drain/grab sample block with integral backpressure regulator and pressure gauge. (Refer to APA6000 Drain/Grab Sample Block with Backpressure Regulator, page XXX.)

The pressure gauge provides an indication of normal analyser operation, and it can be used as a troubleshooting tool. Observations of the pressure reading will help you to isolate possible faults or need for maintenance.

Normal operation:

During normal operation of the analyser, when sample is pumped through the colorimeter, the reading on the pressure gauge will peak and hold at the backpressure regulator setpoint. At the end of the pump stroke, when sample flow stops, the reading on the gauge will drop approximately 3-5 PSI. The gauge reading will stay at this level until the next sample cycle when sample is again pumped through the colorimeter.

Troubleshooting:

Observe the pressure gauge reading throughout a sample cycle.

If the pressure reading drops when the rotary valve is actuated, cross leakage is occurring in the valve. In this case, the valve rotor and stator must be inspected, and the worn part (s) replaced.

If the pressure reading drops during the aspiration (backwards) stroke of the pump, then this also indicates cross-leakage in the valve.

If the pressure reading drops significantly (more than 3-5 PSI) at the end of piston travel when sample is pumped through the colorimeter, then the pump seals are leaking and must be replaced.
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