Hydrostatic Testing - GE Mooney Flowgrid Instruction Manual

A back pressure regulator or relief regulator controls
upstream pressure instead of downstream pressure.
The control action in the pilot is the reverse of a pilot
for a pressure reducing regulator (increasing pressure
in the sense chamber opens the pilot regulator). At no
flow, when the inlet pressure is less than the set point
of the pilot regulator, the pilot is closed and full inlet
pressure loads the spring case through the pilot loading
connection. In this condition, the diaphragm is closed
tightly against the throttle plate. The pressure differential
across the outlet half of the diaphragm adds to the
spring force in closing the Flowgrid regulator (Refer to
Figure 6).
As inlet pressure increases above the set point of the pi-
lot regulator, it will open and start bleeding pressure out
of the spring case faster than it can enter through the
restrictor. Reducing the pressure above the diaphragm
allows inlet pressure to progressively lift the throttling
element off the throttle plate opening the regulator and
satisfying the demand for flow in the upstream system
(Refer to Figure 7).
When upstream pressure decreases, causing the pilot
regulator to close, pilot supply pressure continues to
pass through the restrictor until the control pressure
equals the inlet pressure. The spring force, plus the pres-
sure differential across the outlet half of the throttling
element closes the diaphragm against the throttle plate,
shutting off the flow (Refer to Figure 6).
Adjustment of the restrictor affects the response rate,
stability, and sensitivity of the regulator. Smaller restric-
tor openings result in higher gain (sensitivity) and slower
closing speeds. Larger openings result in lower gain
(greater proportional band), greater stability and faster
closing speeds.

Hydrostatic Testing

All Flowgrid regulators are hydrostatically tested at the
factory prior to shipment according to ISA-S75.19-1989
and MSS-SP-61 standards. If it is necessary to retest the
regulator, follow one of the procedures listed below to
prevent damage to the diaphragm.
Option 1
1. Disconnect and remove all control line(s) and the
pilot from the Flowgrid regulator.
2. Loosen main spring case nuts in a crisscross pattern.
The main spring will lift the spring case as the nuts
are removed.
3. Remove main spring and diaphragm from regulator.
For all 1", 2", 4", 6" (and 10"-V6) Flowgrid Regulators
4. Replace diaphragm with a used
diaphragm that has the thick padded
area cut out leaving the outer sealing
surface (see below).
This area removed
© 2015 General Electric Company. All rights reserved.
For 3" and 4" x 3" Flowgrid Regulators
4. Remove diaphragm but leave diaphragm O-ring in
place. Make sure O-ring is properly seated.
5. Reassemble spring case on Flowgrid regulator.
6. Tighten main bolts in increments using a crisscross
pattern. Torque bolting as indicated on regulator
nameplate (or refer to Table 6, Page 14).
7. Plug spring case loading port, pilot inlet and outlet
taps on Flowgrid regulator.
8. Refer to Table 4 for the maximum hydrostatic test
pressure of each Flowgrid regulator.
9. After hydrostatic test is completed follow the
Dissassembly, Cleaning, and Assembly procedures in
the Maintenance section of this manual
Option 2
1. Disconnect and remove all control line(s) and pilot
from the Flowgrid regulator.
2. Pipe regulator with the inlet, outlet, and loading
connections all common so that pressure is
equalized in the entire regulator during the
hydrostatic test (See Figure 8).
3. Refer to Table 4 for Maximum hydrostatic test
pressure of each Flowgrid regulator.
4. After hydrostatic test is completed follow the
Disassembly, Cleaning, and Assembly procedures
in the Maintenance section of this manual.
Table 4 - Maximum Hydrostatic Test Pressures
End Connection
Screwed & Socket Weld
150# Flange & Flangeless
300# Flange & Flangeless
600# Flange & Flangeless
Flowgrid 250 1
The Flowgrid 250 is a ductile iron construction.
1
A. Inlet connection on regulator body joined to "Tee".
B. "Tee" connected to loading connection on
spring case.
C. Outlet of "Tee" connected to outlet connection on
regulator
Mooney Flowgrid Regulator Instruction Manual | 5
Max. Hydrostatic Test Pressure
2225 psi (153.41 bar)
450 psi (31.02 bar)
1125 psi (77.56 bar)
2225 psi (153.41 bar)
375 psi (25.86 bar)
Figure 8 - Flowgrid Tee Connections