Servomex DF-310E, Руководство оператора

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Troubleshooting and Calibration DF-310E 97
9.4 Troubleshooting
The following Troubleshooting Guide helps the user resolve many of the common operational
situations that occur with the analyzer. Investigate possible remedies in the listed order.
9.4.1 Sample System Leak Test (Low Flow Sensitivity)
By far the most common reason for high Oxygen readings is a leak in the sample delivery
system. Leaks are divided into two types: real leaks and virtual leaks. A real leak is a lack of
integrity in the sample delivery system. A virtual leak is caused by Oxygen that is trapped in the
upstream plumbing and components, such as regulators and filters. This Oxygen is slowly being
purged out of the system. Virtual leaks are most common in new installations.
Determining the nature of the leak is not a difficult task. It is important to be consistent in the
approach and technique. The steps listed below will be helpful toward resolving any leak related
problems.
1) Determine if the high reading is due to a leak or is a real indication of Oxygen level. This
can be easily done by performing a "Flow Sensitivity Test". If the Analyzer is equipped with a
pump, it is recommended that it not be used during the Flow Sensitivity Test. This test requires a
positive pressure sample delivery system. If it is not possible to provide positive sample pressure
to the Analyzer, skip to Step 2. Perform the Flow Sensitivity Test as follows:
a) Establish a flow rate that is within the normal operating tolerances of the
Analyzer. Generally a flow rate between 0.5 LPM or 1.0 SCFH is ideal.
b) Give the Analyzer a couple of minutes to stabilize, and then carefully note the
flow rate and the Oxygen level displayed.
c) Reduce the flow rate by 75%. In a system with good integrity, there should be
little change in the front panel display. If a leak exists, however, the reading will rise noticeably.
Allow it time to stabilize, and carefully note the flow rate and the Oxygen level displayed.
d) Re-establish a normal flow rate and allow the Analyzer to purge for ½ hour. Note
again the flow rate and Oxygen level displayed.
e) Repeat step c. If the Oxygen level stabilizes at a level that is close to the prior
value from step c, then the leak is real. If the reading shows a lower Oxygen level than the prior
value from step c, the leak is probably a virtual leak and continued purging should rectify the
problem.
2) Once it has been determined that there is a leak, the next logical step is to locate it. The
easiest way to locate a leak is to close off the feed to the Analyzer from the sample delivery
system, and to allow the system to pressurize. Apply Snoop® or another type of liquid leak
detector to all of the fittings on the system. Any fitting that shows bubbles should be tightened
or replaced.