Maintenance and Troubleshooting | 5-7
Locating a Plug in the Sample System
If analyzer problems occur, they are most likely related to improper
sample system operation, such as plugs or leaks. Plugs in the sample sys-
tem cause problems in analyzer response time, either to changing process
conditions or to Zero fluid. Leaks are potentially dangerous and will even-
tually lead to corrosion problems.
Detecting a Plug in the Sample System
This is best done by observing the analyzer measurement response time
immediately following a Zero function. A typical response is less than 30
seconds to T90. Observe your analyzer and learn what a normal response
time is. Use the recorded response time as a reference for detecting the
formation of plugs in the sample system.
If the sample response time is longer than normal, it is most likely due
to plugging somewhere in the sample system. The next step is to locate
and remove the plug. The portion of the sample system with the high-
est risk of plugging is the sample inlet and the portion of the sample inlet
most prone to plugging is the valve on the sample probe or process tap.
One way to confirm that a plug is in the sample inlet is to close the Vent
Line Shut Off valve (in the Oven/Sample System Enclosure) and Zero the
analyzer.
Observe the Cell Pressure reading from the STATUS screen, and if the
reading approaches the Zero fluid supply pressure, a plug is present
somewhere in the sample inlet.
To avoid damaging the pressure transducer, do not set the pressure
higher than the sample system rating.
After confirming that the plug is somewhere in the sample inlet, take
all appropriate safety precautions and dismantle the sample system,
starting at the Sample Probe or process tap.
Plugs in the vent side of the sample system are rare. Plugs in the vent sys-
tem cause the aspirator drive air to flow back into the Measuring Cell and,
essentially, simulate a Zero condition.
!
CAUTION
NOTE
To Next Page
Loading...
Need help?
General
