Maintenance, Service and Adjusting Instructions For Safety & Relief Valves
If valves are to be popped by hand, pressure should be at least 75% of set pressure to
p r e v e n t foreign material from becoming caught between seat and disc. The recommend-
ed procedure is to pop the valve" by-running pressure up to set pressure of valve.
Valve failure may be caused by seizing of parts, scored or wire drawn seats and over-
tightening valve in bushing, heavy discharge piping supported directly by valve, operat-
The
ing pressure too close to set pressure of valve and corroded or eroded springs.
first case may be corrected by careful cleaning followed by light sanding of the seating
For correction of the second, safety valves are susceptible of re-machining
surfaces.
of seating surfaces to angles shown on part drawings, or careful hand lapping if damage
is less severe. Springs rarely require replacement, but may be purchased from manu-
facturer as a unit of spare parts should replacement be necessary.
DISMANTLING
1 . Remove lifting gear and/or hood and mark relative positions of pressure screw,
locknut and cap.
2 . Loosen pressure screw locknut and pressure screw to release pressure on spring.
3 . Remove cap.
4. Remove spindle, disc and guide.
5. Mark location of regulator ring(s) if used and remove it.
To reassemble, reverse the above procedure, being careful to return parts to their
marked positions and replace all gaskets. R e - s e t valves according to instructions below.
ADJUSTMENT,
SETTING
and
TESTING
P o p p i n g P r e s s u r e o r C r a c k i n g P r e s s u r e . Make sure of gauge accuracy before begin-
ning. R e m o v e lifting gear and hood exposing pressure screw and locknut. Loosen
locknut and raise pressure until valve pops. If opening pressure is too low, turn down
on pressure screw. If pressure is too high, r e v e r s e pressure screw. A f t e r p r o p e r
pressure has been reached securely tighten locknut.
B l o w d o w n Adjustment, Steam, Air, Gas Valves Only. When popping pressure is
changed, a slight adjustment in blowdown may be required. Raising the popping pres-
sure lengthens blowdown and lowering the popping pressure shortens blowdown. R a i s -
ing the regulator ring toward the disc will increase blowdown and lowering the ring
w i l l decrease blowdown. Regulator ring adjustments should be made a notch at a time
as the adjustment is sensitive. The normal position would be six (6) notches down
from touching the disc, but this figure will vary with conditions.
CAUTION: Re-tighten regulator ring set screw being careful that it rests in notches
without gouging ring surface. Adjusting regulator ring may cause valve to pop if it is
s i m m e r i n g . Keep hands and face clear of outlet.
6-11/6-12
