INSTALLATION, OPERATION, &
MAINTENANCE MANUAL
TITLE: F84L Series Liquid Relief Valve Rev. H Page 8 of 15
5) a.) Bolted-bonnet valve sizes and -2 with retained seat: Carefully install new drag seal / spindle
seal(s) in grooves on spindle. Desco 600 grease should be applied to the outside of these O-
rings, except that, for all -2 valves and –3, –4, and –8 valves below 100 psig, Dow Corning
Molykote 33 or equivalent should be used.
b.) F84L-2 with push-in seat: Carefully push new spindle seal O-rings lubricated with Dow
Corning Molykote 33 into the body grooves using a blunt-tipped instrument or small screwdriver.
Even though they may initially twist, they can be gently worked back and forth until they drop into
the groove.
6) Insert the spindle assembly into the body, making sure that it travels freely on the guide surface.
7) Position the bushing seal on the appropriate shoulder of the bushing.
8) Screw the bushing / seal assembly into the body and tighten using the wrench flats.
9) Assemble the spring washer(s), spring, and lifting rod subassembly (if applicable) into the bonnet.
10) a.) For bolted-bonnet valve sizes, assemble the bonnet, adapter plate (for XXL “C” bonnet),
bolts, nuts, and lockwashers to the body. Torque main bonnet bolts to following value:
12-15 ft-lbs -- 3/8-in bolts marked “B8” on ‘C’ body
25-30 ft-lbs -- 1/2-in bolts marked “B8” on ‘D’ or ‘E’ body
65-70 ft-lbs -- 1/2-in bolts marked “B8” on ‘D’ or ‘E’ body
b.) For the F84L-2, ensure that the body and bonnet threads are clean. Then, firmly screw the
bonnet onto the body.
11) Screw the PA screw and lock nut into the top of the body, with top of screw at previously recorded
value.
12) For lift levers, assemble PA screw and lock nut around lifting rod. Then reassemble the lift nut
and jam nut to previously recorded position. Assemble the lift lever housing and then the
bushing, crush rings, shaft, lift lever, and lock nut.
13) Ensure that the rear bolt and seal are secured in the back of the body (except F84L-2).
14) The valve is now completely assembled and ready to be tested. See Section 4.0.
4.0 VALVE TESTING AND ADJUSTMENT
The following tests and adjustments are necessary for F84L liquid service valves: set pressure and seat
tightness. Blowdown is not adjustable, and is fixed at approximately 15 - 20% (20 – 35% for -2 orifice
size) of set pressure.
4.1 TEST EQUIPMENT
Where practical, the F84L should be set using water or other suitable liquid. To obtain full-flow conditions
and observe blowdown, a sufficiently large pressure vessel will be needed. Setting the valve on air may
damage the seat and is not recommended.
4.2 SETTING / ADJUSTMENT TOLERANCES
Set Pressure: Set Pressure Tolerance
> 70 psig + 3% of specified set pressure
< 70 psig + 2 psi
Seat Tightness: There should be ZERO leakage with inlet pressure at or below:
For F84L -3, -4, -8, -G, -J:
• 0.90 x set pressure, if set pressure > 100 psig
• 0.80 x set pressure, if set pressure < 100 psig
For F84L-2:
• 0.90 x set pressure, if set pressure > 500 psig
• 0.80 x set pressure, if set pressure < 500 psig
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