Vympel CONG Prima 2M - Functional Description of the Sga

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3.4 Functional description of the SGA
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For the electrical, pneumatic, and SGA mounting schematics see Appendices K, I, and E.
The sample extraction device removes gas samples from the gas pipeline at operating
pressure.
Gradually open the shutoff valve (1) in order to evenly fill the SGA with sample gas. In this
way the system can adjust to the operating pressure conditions.
The manometers (6 and 8) make it possible for the operator to continuously monitor this
process.
After passing through the shutoff valve (1), the sample gas enters the SGA’s gravitational
filter. The construction of the filter has one gas inlet and two gas outlets. One of the two
outlets is used to purge filter. The gas that is used to purge the filter flows through the
heating unit (21), the manometer (8), the rotameter (11), and exits the system through the
gas outlet port (14). The gas flow volume in this bypass line can be adjusted using the
rotameter (11). Here, the recommended flow rate is 6 – 10 Nl/min. The heating unit ensures
that the gas temperature remains stable, thereby avoiding the Joule - Thomson effect.
There are two gas pipes within the heating unit (21): the 6mm diameter bypass line for
purging the filter and the 3mm diameter sample gas line that passes through the T-connector
(23) and the heating unit to pressure reduction unit (3).
Depending on the position of the process switch (4), the filtered sample gas flows to the CP
2M’s measuring chamber and/or the inlet port of reference analyzer.
If the process switch is set to “W”, the filtered gas exits the pressure reduction unit at
operating pressure and flows to the CP 2M’s measuring chamber or to the reference
instrument. The pressure reduction unit has one inlet and three interconnected outlets. The
outlets are connected to the process switch (4), the shutoff valve for the reference analyzer
connection, and the CP 2M’s measuring chamber.
If the process switch is set to “HC”, the filtered sample gas passes through T-connection to
the heating unit (21) and from there to the pressure reduction unit (3). The pressure
reduction unit can be set to reduce the gas pressure to the desired parameters in a range
from 1 – 80 bar. The current pressure conditions can be monitored on the manometer (6).
After the gas passes out of the pressure reduction unit it flows to the measuring chamber of
the CP 2M. After the gas leaves the measuring chamber it undergoes further pressure
reduction. The gas flow volume in the analyzer’s measuring chamber can be set to the
desired flow rate using the rotameter (9). The recommended rate here is 0.3 – 0.5 Nl/min.
Subsequently, the sample gas is released into the atmosphere through the SGA’s outlet.