Final Analyzer Connections - Siemens Maxum Edition II Installation Manual

Installation Steps

3.8 Final Analyzer Connections

should have only a very low pressure (0 to 0 to 138 kPa [20 psig].) Install a check valve to
prevent backflow.
When returning a gas sample that can condense, slope it downward to a liquid drain or return
it to the process stream using heat tracing to prevent any condensation.
Properly Route Vent Lines and Exhaust
Run all vent lines and oven exhaust lines outside the shelter. Connect the vents to a location
where the pressure is atmospheric. Don no connect oven or analyzer vents to a variable
pressure source such as a flare header; chromatographic performance will be severely
affected. Backpressure on the oven vent could cause the T-rating of the instrument to be
exceeded, which might become an ignition source. In addition, in some situations it may be
possible for backpressure on oven vents to force hazardous gases into the shelter. See the
comments on hazardous gases at the beginning of this manual.
Liquid Samples
If the sample stream is a liquid, all of the liquid flows should be returned to the process. It is
easiest to return both the sample bypass and analyzer flows together; however, if the
differential pressure available at the analyzer house is less than 10 psig (69 kPa), a separate
power pressure return is required for the analyzer flow (typically 20 cm3/min.) If the liquid could
reverse flow in the process line, install check valves where applicable.
Make sure the return tubing is long enough to reach the connection points. Cap the open ends
of the tubing to prevent contamination.
Vents, Drains, or Means of Returning Samples to the Process Stream
If the sample gas is to be returned to a pressurized line, an atmospheric reference valve (ARV)
is required in the sampling system. The return line should have only a very low pressure (0 to
20 psig [0 to 138 kPa]). Install a check valve to prevent backflow.
When returning a gas sample that can condense, slope it downward to a liquid drain or return
it to the process stream using heat tracing to prevent any condensation. For details on installing
heat tracing, see the "Sampling System" description in this section.
3.8 Final Analyzer Connections
Review the Application Drawing Package, Sampling System sheet and Block Diagram Utility
Connections sheet. Verify that all connections made to this point are correct.
34
WARNING
Installation Manual
Installation Manual, 12/2019, 2000595 Rev 1