Emerson Anderson Greenwood Type 443 - Pilot Set Pressure Adjustment

14
ANDERSON GREENWOOD SERIES 400 PISTON PILOT POPRV
InstallatIon and MaIntenance InstructIons
4 PILOT ADJUSTMENT
4.1 Definitions
Set pressure is defined as the supply pressure
at which the dome pressure is 70% of the
supply pressure. This corresponds to the initial
audible discharge of gas or first steady stream
of liquid from the main valve.
Crack pressure is defined as the supply
pressure at which gas flow begins at the pilot
exhaust.
Reseat pressure is defined as the supply
pressure at which the dome pressure increases
to 75% of supply pressure. The dome pressure
will continue to increase until the supply
pressure decreases to 94% of set.
4.2 Set pressure, standard pilot
4.2.1 Gas service pilot
To adjust the set pressure, a test set-up similar
to that shown in Figure 6 should be used. The
test media should be air. The adjustment screw
should be turned IN most of the way. Increase
the supply pressure to nameplate setting and
slowly back out the adjustment screw until
flow through the pilot exhaust begins. Continue
to slowly back out the adjustment screw until
dome pressure is 70% of the supply pressure
and the supply pressure meets the required
set pressure tolerance of paragraph 4.5. After
adjustment is completed, securely tighten the
jam nut.
To determine reseat pressure, shut off the air
supply and use the accumulator vent valve to
slowly reduce the supply pressure until the
dome pressure is 75% of supply pressure.
Close the shut-off valve and slowly open the
bleed valve. When the dome pressure gauge
reading is zero, the pilot may be removed from
the test set-up.
4.2.2 Liquid service pilot
NOTE
An initial set pressure adjustment may be made with
air as the supply pressure media using a test set-up
similar to that shown in Figure 6 and following the
procedure described in paragraph 4.2.1 above. This
initial set pressure will be approximately 1½% lower
than the set pressure observed when the pilot is
tested on liquid.
To adjust the set pressure, a test set-up similar
to that shown in Figure 7 should be used. The
test media should be water. Some air volume
must be maintained above the water surface in
the accumulator.
Increase the air supply pressure to nameplate
setting and slowly back out the adjustment
screw until water flow through the pilot
exhaust begins. Continue to slowly back out the
adjustment screw until dome pressure is 70%
of the supply pressure and the supply pressure
meets the required set pressure tolerance of
paragraph 4.5.
To determine reseat pressure, shut off the air
supply and use the accumulator vent valve to
slowly reduce supply pressure until the dome
pressure is 75% of supply pressure.
Close the shut-off valve in the water line to
the pilot inlet port and slowly open the bleed
valve. When the dome pressure gauge reading
is zero, the pilot may be removed from the test
set-up.
The optional indicator assembly shown in
Figure 7 may be used for set pressure above
70 psig. If an indicator assembly is used,
slowly increase the supply pressure until the
indicator pin pulls into the indicator assembly
and is approximately flush with the end of the
indicator body. The pressure when the pin pulls
in is the set pressure. Loosen the jam nut,
adjust the adjustment screw, and retighten the
jam nut as required to meet the set pressure
tolerance of paragraph 4.5.
Shut off the air supply and use the accumulator
vent valve to slowly bleed down supply
pressure until the indicator pin ‘pops’ out of the
indicator assembly (full extension of the pin is
approximately
7
/
16”). The pressure when the pin
‘pops’ out is the reseat pressure.
Close the shut-off valve in the water line to
the pilot inlet port and slowly open the bleed
valve. When the dome pressure gauge reading
is zero, the pilot may be removed from the test
set-up.