INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F7000 / 8000 Series Rev. T
Pilot-Operated Safety Relief Valve Page 32 of 43
5.6 F500 PILOT VALVE ADJUSTMENT
(See Illustrations on Pages 25, 26, 27, and 28)
1) The set pressure for the F500 pilot valve may be adjusted by turning the pressure adjusting (PA)
screw, or by changing springs, corresponding diaphragm, or sense piston arrangements. For the
low pressure diaphragm-style pilot, springs and diaphragm parts are matched in a set pressure
range of 15 to 285 psig. For the intermediate pressure piston-style pilot, springs and piston parts
are matched in a set pressure range of 286 to 1480 psig. For the high pressure piston-style pilot,
springs and piston parts are matched in a set pressure range of 1481 to 6000 psig. Contact Flow
Safe to verify the proper parts for the desired set pressure.
2) Attach pilot valve assembly to the test tank with the cap removed and the PA screw turned out to
below where the set point is believed to be.
3) Slowly increase inlet pressure to set point, which occurs when dome pressure decreases to the
percentage of inlet pressure listed in 5.2.1 or the main valve opens as described in 5.2.2.
4) Before set point is reached, dome pressure and inlet pressure should increase together until dome
pressure stops rising at approximately 93 - 94% of set pressure. As inlet pressure increases
further, first bubble (or first flow of liquid) from the pilot exhaust should occur and dome pressure
should begin decreasing at approximately 96 - 98% of set pressure. (NOTE: If optional Set Point
Indicator is included, the set point indicator pin should move in when dome pressure has
decreased to approximately 86% of inlet pressure.)
5) If dome pressure does not drop to the specified value at the required set pressure, adjust the
pressure adjusting screw as necessary. Decrease pressure to 90% or less of set pressure,
allowing inlet and dome pressure to equalize, before checking set pressure again. (NOTE: If
optional Set Point Indicator (SPI) is included, the SPI pin should return to the out position when
inlet and dome pressure equalize.) Tighten down the PA screw lock nut when adjustment is
complete.
6) If the pilot leaks from exhaust at pressures less than first bubble point, as described above, or if set
point cannot be properly set , discontinue the test and disassemble the valve and check parts.
7) Install and tighten the cap onto the PA screw.
8) Repeat the test to verify repeatable performance.
9) With the pilot valve assembly pressurized to just under set point, inspect all tubing, connections,
and fasteners for leaks.
10) Backflow preventer test:
a) Attach a pressure supply line to the exhaust port of the test fixture block.
b) Reduce the pressure in the test tank to approximately 50% of the pilot valve set pressure or 50
psig, whichever is lower.
c) Slowly increase the pressure through the exhaust port. As this pressure increases above the
test tank pressure, the dome pressure gage should begin to increase and read the same as the
exhaust port pressure. If this occurs, the backflow preventer is working properly. If this does
not occur, disassemble and inspect the parts.
To Next Page
Loading...
Need help?
General
