Emerson Anderson Greenwood 93 Series Installation And Maintenance Instructions Manual page 5

ANDERSON GREENWOOD SERIES 93T PILOT OPERATED SAFETY RELIEF VALVES
INSTALLATION AND MAINTENANCE INSTRUCTIONS
4.5 Adjustment tolerances
Pilot action Set pressure
[1]
Snap 2"WC to 1.0 psi
1 psi to 15 psi
-2"WC to 1.0 psi
-1.0 psi to -14.7 psi
Modulating 2"WC to 1.0 psi
1.0 psi to 15 psi
-2"WC to 1.0 psi
-1.0 psi to -14.7 psi
NOTES
1. Snap action - dome pressure decreases rapidly with a "snap" to 15% ± 10% of set pressure at set pressure.
Modulating action - dome pressure decreases slowly to 30% ± 5% of set pressure and recovers to 60% ± 10%
of set pressure at set pressure.
2. Pilot seat should be bubble tight at dome recovery for "snap" pilot action and at 90% of set pressure for
"modulating" pilot action non-marine.
4.6 Definitions
Set pressure is defined as that pressure where the dome pressure is 15% of the supply pressure.
Crack pressure is defined as the supply pressure where gas flow begins at the pilot exhaust.
Adjustable
pressure
regulator
(relieving type)
Supply
pressure gage
Supply port
Supply
Supply
Vent
pressure
Accumulator
FIGURE 4 - Optional test set-up
Set pressure
tolerance
±3%
±3%
±3%
±3%
±3%
±3%
±3%
±3%
½" FNPT
ports
½" pipe
Minimum crack pressure as %
of nameplate set
90
92½
90
92½
90
92½
90
92½
Pressure adjustment
Pilot valve to be set
Blowdown adjustment
Dome pressure gage
Pressure adjustment
Blowdown adjustment
Dome pressure
Supply pressure as % of set for
dome pressure recovery
[2]
90 ± 1
92½ ± ½
90 ± 1
92½ ± ½
100
100
100
100
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