Consolidated 1982 Series Safety Relief Valve Manual
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XIII. Setting and Testing
Safety Relief Valve Performance
Satisfactory safety relief valve operation requires
that the valve seat shall be satisfactorily tight at the
operating pressure (normally about 90% of the set
pressure). On gases and vapors, the valve should
pop at set pressure after the usual slight warning.
Blowdown Adjustment
(Reseating Pressure)
Note: Unless the test stand capacity is equal to
or greater than that of the valve, Do not attempt
to set blowdown. Simply return the adjusting
ring or guide to the original position.
If longer or shorter blowdown is required, it can be
obtained as follows:
a. To increase blowdown (lower reseating pressure),
the adjusting ring must be raised by moving the
notches from left to right past the ring pin hole.
b. To decrease blowdown (raise reseating pressure),
the adjusting ring must be lowered by moving the
notches from right to left past the ring pin hole.
A. Setting and Testing after
Reconditioning
Before putting the reconditioned valve in service,
it must be set to open at the required set pressure.
Although the valve can be set on the service
installation, it is more convenient to set the valve and
check seat tightness on a test stand.
When using a test stand, the valve should be set to
open at the cold differential set pressure as shown
on the nameplate. The cold differential set pressure
is the set pressure corrected to compensate for back
pressure and/or operating temperature.
B. Setting the Valve
Set the valve on clean air. Before mounting the valve
on the test stand, remove all dirt, sediment or scale
from the test tank nozzle and the inlet port of the
valve. Be sure that the test gauge is accurate and
has recently been calibrated on a dead weight gauge
tester.
Mount the valve on the test stand. Slowly bring the
pressure up in the test tank to the cold differential
set pressure. If the valve opens before the desired
pressure is reached, additional compression is
required on the spring. Hold the spindle to prevent
rotation and turn the adjusting screw clockwise. If
the valve does not open at the desired pressure,
maintain the required pressure in the test tank
and slowly release the compression on the spring
by turning the adjusting screw counterclockwise
until the valve opens. Continue adjustment until
the valve opens at the desired pressure. Be sure
to hold the spindle when turning the adjusting
screw. The spindle should be centrally located
within the adjusting screw as hard rubbing of the
spindle against the side of the adjusting screw as
hard rubbing of the spindle against the side of the
adjusting screw may cause poor valve action.
After the required set pressure is obtained, tighten
the adjusting screw nut and repeat test. At least two
repeat openings at the same pressure should be
obtained to be sure that the valve is set accurately.
