Cashco PGR-1 - Manual (Page 2)

IOM-PGR-1 2
IV. PRINCIPLE OF OPERATION
1. When a loading pressure – P
Load
– is applied to
the top side of a diaphragm, the outlet controlled
pressure – P
2
– will balance at approximately
.90 – .98 of the loading pressure - P
L
.
2. Movement occurs as pressure variations register
on the diaphragm. The registering pressure is the
outlet, P
2
, or downstream pressure. The loading
pressure fl uid op pos es di a phragm move ment.
As outlet pres sure drops, the loading pressure
push es the di a phragm down, opening the port; as
outlet pres sure increases, the diaphragm pushes
up and the port opening closes.
3. A diaphragm failure will tend to cause the reg u la tor
to fall below setpoint. A loss of loading pres sure
while inlet pressure is imposed will cause the
regulator to fail close.
V. STARTUP
1 Start with the block valves closed.
2. Rotate the adjusting screw (47) on the pilot valve
CCW so that main regulator is trying to be con trolled
at 0 psig pressure. DO NOT rotate the adjusting
screw on the stabilizer, stabilizer was preset and
calibrated at the factory.
3. DO NOT rotate knob on metering valve, it was
preset at the factory at 2.5 to 3 full revolutions from
closed position. DO NOT close metering valve.
4. If it is a “hot” piping system, and equipped with
a bypass valve, slowly open the bypass valve
to preheat the system piping and to allow slow
ex pan sion of the piping. Closely monitor outlet
(down stream) pressure via gauge to ensure not
over-pressurizing. NOTE: If no bypass valve is
in stalled, extra caution should be used in starting
up a cold system; i.e. do everything slowly.
5. Crack open the outlet (downstream) block valve
to approximately 10% full open.
6. Slowly open the inlet (upstream) block valve to
about 25% open. Rotate the adjusting screw
(47) on the pilot valve CW to increase setpoint
SECTION V
CAUTION
DO NOT HYDROSTATIC TEST THROUGH AN IN STALLED
UNIT; ISOLATE REGULATOR FROM TEST. The "OUTLET
RATING" as printed on the name plate is the rec om mend ed
“upper op er at ing limit” for the sens ing di a phragm. Higher
pres sures could cause internal dam age. In ad di tion, note
on the nameplate that the Inlet and Outlet pres sure and
temperature ratings are at different levels.
CAUTION
Do not walk away and leave a bypassed reg u la tor unat-
tended!
pressure upwards until the main valve is fl owing.
Observe the outlet pressure gauge to ensure not
overpressurizing.
7. Continue to slowly open the inlet (upstream) block
valve until fully open.
8. Continue to slowly open the outlet (downstream)
block valve, especially when the downstream pip-
ing system isn’t pressurized. If the outlet (down-
stream) pressure exceeds the desired pres sure,
close the inlet block valve and go to Step 2. Close
bypass valve approximately 25%, and re peat
pro ce dure.
9. When fl ow is established steady enough that the
outlet (downstream) block valve is fully open, begin
to slowly close the bypass valve if installed.
10. Develop system fl ow to a level near its expected
normal rate, and reset the regulator set point by
rotating the adjusting screw (47) on the pilot valve
CW to change the setpoint to the desired outlet
pressure level. If system pressure is unstable
rotate knob on metering valve in quarter turn in-
crements CW or CCW to combat instability. DO
NOT rotate knob more than 6 full revolutions from
the closed position.
11. Reduce system fl ow to a minimum level and
observe pressure set point. Outlet pressure will
rise from the set point of Step. The max i mum rise
in outlet pres sure on de creas ing fl ow should not
exceed the 10%. If it does, consult factory.
SECTION IV