Cla-Val 790-63 - Manual (Page 9)

Relief Valve Applications 750
Series Valves
The following instructions are for valves
equipped with a Model CRL Pressure
Relief Pilot Control.
Due to the nature of intended use, the
system being protected with the relief
valve will most likely not be able to fur-
nish the pressure source needed to
establish the proper setpoint of the pilot
control. Due to this fact, in most
instances, the relief valve setting proce-
dures will either have to be carried out at
other locations or an auxiliary pressure
source will have to be supplied at the
site in order to carry out the following
procedure.
Remove the adjustment cap and
increase tension on the range spring by
means of the adjustment screw (turn
clockwise) until maximum spring load is
attained.
Slowly introduce inlet pressure to the
valve at the desired setpoint value.
Bleed all air.
Gradually decrease tension on the
range spring by means of the adjust-
ment screw (turn counterclockwise) until
flow is initiated through the valve.
Reduce system pressure back to normal
value. Tighten the adjustment screw
lock nut and replace the adjustment cap.
The valve is now ready for service.
In most instances, the 700 Series Cla-Val
Control valves will be shipped complete
with a pilot control system mounted on the
Model 100-42 valve. Consult the appropri-
ate start up and operation instructions for
the pilot control used before pressurizing
the system. IT IS IMPORTANT THAT THE PRESSURIZA-
TION AND DEPRESSURIZATION OF ALL
INSTALLATIONS BE CARRIED OUT IN A MAN-
NER TO PREVENT IMPOSING A REVERSE
PRESSURE CONDITION ON THE CLA-VAL
MODEL 100-42 VALVE. PRESSURIZATION OF
THE SYSTEM SHOULD BE ACCOMPLISHED
BY PRESSURIZING THE INLET SIDE FIRST. DEPRESSURIZATION OF THE SYS-
TEM SHOULD BE ACCOMPLISHED BY
DEPRESSURIZING THE OUTLET SIDE
FIRST. FAILURE TO FOLLOW THIS
PROCEDURE COULD RESULT IN DIS-
LODGEMENT AND/OR DESTRUCTION
OF THE RUBBER LINER.
Pressure Reducing
790 Series Valves
The following instructions are for
valves equipped with a Model CRD
Pressure Reducing Pilot Control.
Remove the adjustment cap and back
off adjustment screw setting (turn
counterclockwise) of the CRD
Pressure Reducing Pilot Control to fully
relieve all loading on the range spring.
Slowly open the upstream main line
block valve to pressurize the inlet sec-
tion of the valve.
Bleed any entrapped air from the con-
trol chamber of the valve and tubing
sections by loosening fittings at the
highest points. Retighten fittings.
Install gauge on downstream port of
CRD.
Slowly increase tension on the range
spring, by means of the adjustment
screw (turn clockwise) until the desired
downstream pressure is attained. Use
a gauge.
Open the downstream main line block
valve.
If required, reset the pilot adjustment
screw setting to obtain the downstream
pressure desired.
Tighten the adjustment screw lock nut
and replace the adjustment cap.
Back Pressure Control
750 Series Valves
The following instructions are for
valves equipped with a Model CRL
Back Pressure Pilot Control.
Remove the adjustment cap and
increase tension on the range spring,
by means of the adjustment screw
(turn clockwise) until maximum
spring load is attained.
Slowly open the upstream main line
block valve to pressurize the inlet
section of the valve.
Bleed any entrapped air from the
control chamber of the valve and tub-
ing sections by loosening fittings at
the highest points. Retighten fittings.
Open the downstream main line
block valve.
Gradually decrease tension on the
range spring by means of the adjust-
ment screw (turn counterclockwise)
until upstream pressure decreases to
the desired setpoint.
Tighten the adjustment screw lock
nut and replace the adjustment cap.
PLACING VALVE INTO OPERATION
START-UP INSTRUCTIONS
Vent the upstream section to fully relieve
pressure in the inlet section and control cham-
ber of the Model 100-42 valve.
If the valve liner is to be inspected or
replaced, remove the valve from the main line.
The following procedure should be followed
when taking the Model 100-42 valve out of
service.
Close the upstream main line block valve
first. Then close the downstream main line
block valve.
Vent the downstream section to fully relieve
pressure in the outlet section of the valve.
Taking Valve Out of Service
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Important Procedure for All Installations:
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