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TM 10-3835-231-13
(a)
Upstream Components.
1 The PILOT CIRCUIT INLET VALVE (1) is an upstream isolation or block needle valve and is
always kept open while operating.
2 The UPSTREAM PRESSURE GAUGE (2) monitors the pressure on the upstream side of the
pressure regulator.
3 The SEDIMENT TRAP DRAIN valve (3) is the upstream drain valve and is located at the bottom
of the sediment trap (4).
4 The sediment trap (4) is used as a settling tank to remove solids from the fluid.
5 The WYE strainer (5) contains a 100 mesh screen which removes particles that were not
removed by the sediment trap (4).
6 The AIR BLEED VALVE (6) is an upstream vent ball valve that when opened while operating,
vents air out of the system while at the same time flushing out the WYE strainer (5).
7 The needle valve (7) with a 100 mesh strainer is a preset valve that should not be tampered with
except for periodic strainer cleaning.
8 The upstream BACK PRESSURE PILOT BYPASS VALVE (8) bypasses the back pressure pilot
valve and should not be open during operational conditions.
9 The upstream pilot or back pressure pilot valve (9) controls the pressure regulator based on the
upstream pipeline conditions.
(b)
Downstream Components.
1 The downstream pilot or back pressure pilot valve (10) controls the pressure regulator based on
the downstream pipeline conditions.
2 The DOWNSTREAM PRESSURE GAGE (11) indicates the pressure on the downstream side of
the pressure regulator.
3 The STRAINER VENT valve (12) is opened only to relieve the air out of the pressure regulator.
4 The DOWNSTREAM PILOT ISOLATION VALVE (13) is always kept open while operating the
pressure regulator.
5 The PILOT CIRCUIT OUTLET VALVE (14) is the downstream isolation valve and is to be kept
open while operating the pressure regulator.
NOTE
Upon pipeline startup, the upstream AIR BLEED VALVE (6) should be opened to
ensure that all air is removed from the pressure regulator. The downstream
STRAINER VENT valve (12) should also be opened to ensure that all air has been
removed. Once a continuous flow of fluid from the vent valves has been noted and
one is confident that all air has been removed from the pressure regulator, tightly
close valves (6) and (12).
2-5
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