3
ANDERSON GREENWOOD
SERIES 81 SPRING OPERATED PRESSURE RELIEF VALVES
INSTALLATION AND MAINTENANCE INSTRUCTIONS
4 VALVE ADJUSTMENT
4.1 General
Two adjustments are provided on gas service
valves, one for adjusting the opening pressure
and one for adjusting the closing pressure.
4.2 Set pressure
Turn spring adjustment screw on bonnet in most
of the way. Increase pressure to desired level
and back out screw until valve pops. Lock screw
with jam nut and retest. Readjust as required.
4.3 Reseat pressure
To adjust blowdown, turn blowdown adjustment
screw IN to shorten blowdown; OUT to increase
blowdown.
Note:
if volume of test set up is too small,
blowdown will be set too short even though
pressure gauge indicates it to be correct.
Refer to Section 4.5.
4.4 Adjustments tolerances
Two adjustments are provided on gas service
valves, one for adjusting the opening pressure
and one for adjusting the closing pressure.
SET PRESSURE RANGE
psig
kpag
Valve operating characteristic Tolerance*
Above 70
Above 483
Set pressure
±3%
70 and below
483 and below
Set pressure
±2 psi (±13.8 kpa)
100 and above
689 and above
Cracking pressure
95%
50 to 99
345 to 683
Cracking pressure
90 %
Below 50
Below 345
Cracking pressure
85%
100 and above
689 and above
Reseat pressure
93%
50 to 99
345 to 683
Reseat pressure
90%
Below 50
Below 345
Reseat pressure
80%
* Percent tolerance is of specified set pressure
3.4 Soft goods repair kit
The part numbers for soft goods repair kits are listed below. Each kit contains the seat and seals
for all pressure ranges indicated.
Orifice
TFE/KEL-F
Set pressure range
Vespel
Set pressure range
psig
kpag
psig
kpag
4.5 Adjusting equipment
Where practical, valves should be set using
an accumulator large enough to accurately
read and set blowdown. For a -4 orifice up
to 4000 psig (27579 kpag), -6 orifice up to
1410 psig (9722 kpag) and a -8 orifice up to
600 psig (4137 kpag), a four cubic foot (0.113 m
3
)
accumulator is recommended. The supply pipe
to the valve should be the same size as the inlet
or larger and not more than 10” (254 mm) long.
For all other valves, or if an accumulator is
not available for the sizes listed above, the
blowdown may be set using the following
method.
Turn the blowdown adjusting bolt all the way in
until it just touches the guide, then turn it out
the number of turns listed in the table.
F
04.4805.007
20-750
138-5171
04.4805.008
≥ 751
≥ 5178
G
04.4805.009
20-750
138-5171
04.4805.010
≥ 751
≥ 5178
H
04.4805.011
20-750
138-5171
04.4805.012
≥ 751
≥ 5178
J
04.4805.013
20-750
138-5171
04.4805.014
≥ 751
≥ 5178
