Emerson Anderson Greenwood 9300 Series Installation And Maintenance Instructions Manual page 26

Anderson Greenwood SerieS 9300 Pilot oPerated Safety relief ValVeS
InstallatIon and MaIntenance InstructIons
3.6 Pilot adjustment for flowing modulating or
snap action pilots (series 91, 93, and 93t pilots)
the pilot may be set separate from the main
valve provided there is access to a pilot test
system similar to the one shown in figure 14.
3.6.1 Adjustment of set pressure
1. install the pilot valve onto the pilot test
system, and attach gage sensing lines to
the supply and dome connections.
2. remove the cap.
3. Screw the set pressure adjustment screw
clockwise until it is screwed in 80% to 90%.
4. increase the supply pressure to nameplate
setting and slowly back out the set pressure
adjustment screw until flow through the pilot
exhaust begins.
5. Continue to back the set pressure adjustment
screw out until the dome pressure is 70%
of the supply pressure. When the dome
pressure reaches 70% of the supply
pressure read the supply gage pressure.
if it is below set pressure, you will need to
tighten down on the pressure screw, or back
off it if you are high. tighten the locknut
once the desired set pressure is achieved.
note: set pressure on a vacuum pilot is
evidenced by a rapid change of the dome
pressure (0 gage) to the supply pressure.
a slow ramp speed is recommended on low
set valves in order to obtain true reading of
set pressure.
6. Check the pilot exhaust vent for leakage.
the pilot shall be bubble tight up to crack
pressure shown in 3.6.3. also, check upper
pilot vent for leakage. there should be
0 leakage from the upper vent.
3.6.2 Reseat pressure
1. turn the blowdown adjusting screw
clockwise to decrease the reseat pressure
or counterclockwise to increase the reseat
pressure.
2. a small interaction between set pressure
and reseat pressure adjustments will occur;
therefore, it may be necessary to readjust
the set pressure after setting reseat pressure.
3.6.3 AdjustMent tolerAnces
Pilot action set press.
Snap 4" WC to 7" WC
Snap 7" WC to 1.0 psig
Snap above 1 psig
Snap -4" WC to -7" WC
Snap -7" WC to -1.0 psig
Snap -1 PSi to -14.7 psig
Modulating action 4" WC to 7" WC
Modulating action 7" WC to 1.0 psig
Modulating action above 1.0 psig
Modulating action -4" WC to -7" WC
Modulating action -7" WC to -1.0 psig
Modulating action -1.0 PSi to -14.7 psig
note: if the blowdown adjusting screw has
been removed or turned to either extreme,
positioning it midway will aid in obtaining
the correct reseat pressure. there are
approximately 7 to 8 turns to obtain full travel
of the adjustment. Midway from either end
should produce a blowdown for snap action.
for modulating pilot action, back the
adjustment screw out counterclockwise.
3. Cycle the pilot valve a minimum of 5
times to assure that dome pressure
reduction at set pressure is consistent.
increase the pressure very slowly in order to
obtain an accurate reading of the cracking
pressure and to expose any erratic
performance.
note: cracking pressure on vacuum pilots
is that pressure at which the initial dome
pressure change is noted.
4. Hold the pilot valve at set pressure to obtain
the dome pressure reading. for modulating
pilots, dome pressure shall be read with
the inlet at 105% of set pressure.
note: the first 4 steps should be completed
before this step is undertaken.
on snap action pilots, the dome pressure
decreases rapidly with a "snap" to
15% ± 10% of set pressure.
on modulating action pilots (Series 90),
the dome pressure decreases slowly to
30% ± 5% of set pressure and recovers to
60% ± 10% of set pressure at set pressure.
5. after desired pilot action is set, verify pilot
seat tightness. this is accomplished by
checking the pilot exhaust vent for leakage.
the pilot should be bubble tight up to crack
pressure as shown in 3.6.3. Be aware
of crack pressure changes between set
pressure ranges.
set press. crack press. reseat press.
tolerances % set % set
± .2" WC 75% 90% ± 1
± 3% 90% 90% ± 1
± 3% 95% 92% ± 1
± .2" WC 75% 90% ± 1
± 3% 90% 90% ± 1
± 3% 95% 92% ± 1
± .2" WC 75% 100%
± 3% 90% 100%
± 3% 95% 100%
± .2" WC 75% 100%
± 3% 90% 100%
± 3% 95% 100%
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