5-6 | Model 900 ADA / Model 930 Sulfur Pit Analyzers
Preventing, Detecting, and Locating a Plug in the
Sample System
Preventing a plug in the sample system:
While various factors can contribute to plugs in the sample system, plugs
can be avoided in many cases by:
• Maintaining the ambient temperature around the analyzer, and the
operating temperatures for each analyzer temperature zone.
From the MAI screen, check the real-time temperature for each
Temperature Zone and compare it to its Set Point temperature (on the
TStPt screen).
Also, verify the ambient temperature surrounding the analyzer and
the operating temperature of the ASR900 Sample Probe is at least 10 °C
(18 °F) above the sample stream temperature. It is extremely important
to maintain a relatively stable ambient temperature in the vicinity of
the analyzer, with no rapid temperature fluctuations.
• Performing regular maintenance (see “Analyzer Preventive
Maintenance Schedule” in this chapter).
• Observing the analyzer response time regularly and taking action im-
mediately if longer response times are noticed (perform maintenance
on components suspected to be restricted or plugged).
Detecting a plug in the sample system:
This is best done by observing the analyzer’s measurement response time
immediately following a Zero. A typical response is less than 30 seconds
to T
90
(excludes sample system). Observe your analyzer regularly to learn
what a normal response time is and keep records of response times after
a Zero. Use the recorded response times as a reference for detecting the
formation of plugs in the sample system (that is, longer response times).
The section of the sample system with the highest risk of plugging is the
sample inlet and the section of the sample inlet most prone to plugging is
the Sample Probe Valve. One way to confirm that a plug is in the sample
inlet is to close the Vent Valve (on the ASR900 Sample Probe) and Zero the
analyzer. Plugs in the sample outlet (or vent side) of the sample system
are rare.
(MAI) RUNF6 81..8
(TStPt) RUNF4 01..4
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