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5.1 Overview
This section provides information about preventive maintenance and replacing damaged parts. The topics
covered in this section are:
•
Preventive maintenance of the meter body barrier diaphragms and process piping to the
transmitter.
•
Replacement of damaged parts such as the transmitter Printed Wiring Assembly (PWA) and
meter body.
5.2 Preventive Maintenance Practices and Schedules
The ST 800 transmitter does not require any specific maintenance at regularly scheduled intervals.
However, it is recommended that you perform these typical inspection and maintenance routines on a
schedule that is dictated by the characteristics of the process medium and if blow-down facilities or purge
systems are being used.
•
Check piping for leaks.
•
Clear piping of sediment or other foreign matter.
•
Clean the transmitter process heads, including the barrier diaphragms.
5.3 Inspecting and Cleaning Barrier Diaphragms
Depending on the characteristics of the process medium, sediment or other foreign particles may collect
in the process head cavity/chamber and cause faulty measurement. In addition, the barrier diaphragm(s) in
the transmitter meter body may become coated with residue from the process medium. The latter is also
true for external diaphragms on flange-mount and remote seal type transmitters.
In many cases, you can readily remove the process head(s) from the transmitter meter body to clean the
process head cavity and inspect the barrier diaphragm(s). For flange-mount and remote seal diaphragms,
you may only need to run a purge line in the tank to rinse off the face of the diaphragm(s).
The following procedure comprises the general steps for inspecting and cleaning barrier diaphragms. You
may have to modify these steps to meet your particular process or transmitter model requirements.
shows an exploded view of a Differential Pressure (DP) transmitter meter body for reference. For
disassembly/reassembly purposes, Gauge Pressure (GP) and Absolute Pressure (AP) transmitters are
similar.
It is recommended that you remove the transmitter from service and move it to a clean
area before disassembling it.
88
5 Maintenance
ST 800 Pressure Transmitter User's Manual
Figure
Revision 15
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