4
4 VALVE ADJUSTMENT
4.1 General
The only adjustment required for the Type 81P valve is the set pressure. The reseat pressure
is not adjustable. Reseat will occur at approximately 75% to 80% of set pressure.
4.2 Proof test
The spindle seals and bonnet seal of the Type 81P valve shall be checked for integrity by
pressurizing the outlet with 30 psig (207 kpag) of air. A soap solution shall be applied to the
exterior joints of the bonnet, including across the vent hole. There shall be no evidence of
leakage.
4.3 Set pressure
Type 81P liquid valves marked with the UV code stamp (relief capacity in volume of liquid per
time, GPM) shall be set using water and a 50 gallon pressure vessel.
When setting the valve using water, turn the spring adjustment screw on the bonnet in most
of the way. Increase the pressure to 107% ± 2% of nameplate set and back out screw until
the valve 'pops' or 'gushes' liquid. Set pressure is defined as 93% of that pressure where the
valve 'pops'.
Example liquid
English liquid
International liquid
Nameplate set =
75 psig
5.2 barg
'POP' or 'GUSH' =
(107% ± 2%) 75 = 78.75 to 81.75 psig
(107% ± 2%) 5.2 = 5.4 to 5.6 barg
Actual 'POP' =
80 psig
5.5 barg
Actual set =
80 (.93) = 74.4 psig
5.5 (.93) = 5.1 barg
ANDERSON GREENWOOD
TYPE 81P DSO PRESSURE RELIEF VALVES
MAINTENANCE INSTRUCTIONS
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 and the lubricant specified in paragraph 3.3.
MATERIAL
Orifice
NBR
FKM
EPR
G
04.4805.030
04.4805.033
04.4805.072
J
04.4805.031
04.4805.034
04.4805.073
LUBRICANTS
Part
Set pressure
Orifice
Lubricant
Spindle seals
50-300 psig (3.4 - 20.7 barg)
G
Dow Corning FS3451
50-100 psig (3.4 - 6.9 barg)
J
Dow Corning FS3451
Spindle seals
Above 300 psig (20.7 barg)
G
Desco 600
Above 100 psig (6.9 barg)
J
Desco 600
Thread and adjusting bolt tip
All
G and J
Dow Corning 33
