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CROSBY STYLE JQ 4 IN. PRESSURE RELIEF VALVE
INSTALLATION AND MAINTENANCE INSTRUCTIONS
8.6 Test for Start-to-Discharge (Set Pressure)
WARNING
Failure to follow these instructions can cause
damage to the valve and potentially personal injury
from an over pressure event.
A person should NEVER stand directly over or in
front of or look directly into a relief valve when the
tank or test stand is pressurized. The relief valve
could suddenly "pop" open blowing gas, dirt and
other debris into the person's face and eyes.
Mount the valve on the test stand (13.1.6). Be
sure all parts are clean to prevent damage
to valve seats. Place the Gasket (44) and the
Filler (43) on the Adapter Flange (40) on the test
stand (13.1.6). Bolt the safety valve proper to
the Adapter Flange (40) above the Filler (43) and
screen using a Safety Mechanism Washer (16).
Apply pressure slowly as the set pressure is
approached to assure accurate determina tion
of set pressure. If the set pressure is not within
the limits shown in Section 3.2, reduce the
pressure on the valve, loosen Lock Nut (4) and
turn the Adjusting Bolt (3) clockwise to increase
set pressure or counterclockwise to reduce set
pressure; tighten Lock Nut (4). Then, retest the
valve for the set pressure. Failure to reduce
pressure before adjusting the valve can cause
turning on the seating surfaces and damage to
the lapped surfaces.
8.7 Test for Vapor Tightness
WARNING
Failure to follow these instructions can cause
damage to the valve and potentially personal injury
from an over pressure event.
A person should NEVER stand directly over or in
front of or look directly into a relief valve when the
tank or test stand is pressurized. The relief valve
could suddenly "pop" open blowing gas, dirt and
other debris into the person's face and eyes.
After setting the start-to-discharge pressure
correctly, reduce the pressure to the required
vaportight pressure (240 psig for a set pressure
of 300 psig and 300 psig for a set pressure of
360 psig), screw the Casing (8) and the Cap (1)
with Test Diaphragm (46) on the valve and hold
for three minutes. Observe valve vaportightness
as indicated by a soap solution over the
⅟ ₁₆ in. hole in the top of the Test Diaphragm (46).
Remove the Cap (1) and the Casing (8) with the
Test Diaphragm (46). If the valve is not vaportight
at the minimum required pressure, dismantle
and repair the valve (8.2 to 8.7). If vaportightness
and set pressure meet the above requirements,
remove the Lock Pin (12), lower the Adjusting
Ring (11) two more notches, reinstall the Lock
Pin (12) and record the test data as required by
the local code.
8.7.1 Install Cap (1) and Casing (8)
Install a new Upper Diaphragm (2) and lubricate
the threads on the casing (5.2.3). Tighten the
Casing (8) with a strap wrench (with about one-
foot leverage) or by inserting a bar through the
handle on the Cap (1). Care must be taken not
to damage the Upper Diaphragm (2). Too much
leverage will cause the lead Base Washer (15) to
flow. Be sure the proper data plate corresponding
to the set pressure and shop number of the valve
is applied.
9 RECONDITIONING AND TESTING OF
ELASTOMERIC SEAT VALVES
9.1 Disassembly of Safety Valve for
Initial Inspection
CAUTION
Failure to follow these instructions may result in
improper function of the valve.
Always wear proper PPE.
The valve should be carefully dismantled in
accordance with instructions in this manual.
Valve parts should be thoroughly cleaned after
disassembly per Section 12.1.
9.1.1 Remove Cap (1) and Casing (8)
Remove the Cap (1) and the Casing (8) from the
Base (17). Do not support the valve upside down
on the Spindle (6).
9.2 Required O-ring (10E) Replacement
The seat seal O-ring (10E) of the elastomeric
seat seal design valve must be replaced each
time that the valve is tested and examined.
9.2.1 Remove Adjusting Bolt (3)
Loosen the Lock Nut (4) with a pipe wrench on
the Adjusting Bolt (3). The Lock Nut (4) may be
left on the Adjusting Bolt (3) to approximate the
spring setting after reassembly if so desired.
Remove the Adjusting Bolt (3) with a strap
wrench or suitable tool. If the Disc Guide (7)
is loose on the Base (17), it should be held in
place during this operation to avoid distorting
the small lock screws. A strap wrench has been
proven effective if this is necessary.
9.2.2 Remove the Disc Assembly (10)
Lift out the Spring (5), the top Spring
Washer (9), the Spindle (6) and the Bottom
Spring Washer (19). Remove the Disc
Assembly (10) by lifting it out carefully with
fingers. Be very careful not to mar the
Nozzle (13) surfaces; damage to the seat will
cause the valve to leak.
9.2.3 Teardown of Disc Assembly (10A-E)
To disassemble the Disc Collar (10D) and
O-ring (10E) from the Disc Assembly (10A-E),
the Spiral Pin (10C) must be driven out
from a locked position. This operation may
conveniently be done using a ¼ in. diameter
drift pin having a long driving section. To
facilitate removal, lubricate the pin with a good
penetrant such as Neolube (colloidal graphite
suspended in alcohol). Then, remove the Disc
Collar (10D) from Disc Assembly (10A-E). If
difficulty is encountered in the disassembly
of the Disc Collar (10D), carefully remove the
Disc Collar (10D) by inserting a small pry bar
(screwdriver) in the clearance slot provided
between the Disc (10A) and the Disc Collar (10D).
9.2.4 Inspection
If inspection at this point does not reveal
corrosion or contamination, proceed to
Section 9.3.4. If the valve is not clean, then
continue with Section 9.2.5.
9.2.5 Remove Disc Guide (7)
First, loosen the Lock Screws (18) with a
hex wrench. Then, turn the Disc Guide (7)
counterclockwise until it is free from the
Base (17).
9.2.6 Remove the Nozzle (13)
Remove the Lock Pin (12) and then the Adjusting
Ring (11) from the Nozzle (13). Next, unscrew the
Nozzle (13) from the Base (17). Be careful not to
mar the seating surface. Damage to the seating
surface will cause the valve to leak. Remove the
O-ring (14) and discard.
9.3 Reassembly of the Safety Valve Proper
9.3.1 Install Nozzle (13)
Prior to assembly of the Nozzle (13) and the
Nozzle O-ring (14) to the Base (17), clean the
parts and coat the guiding, sealing and threaded
surfaces with a thin film of nonreactive lubricant.
Place the O-ring (14) in the O-ring groove of the
Nozzle (13). Next, thread the Nozzle (13) to the
Base (17); make sure the O-ring (14) is retained
fully within the confines of the groove. Apply
sufficient torque to ensure that the Nozzle (13)
will not move and that metal-to-metal contact is
made between the Nozzle (13) and Base (17).
Screw the Adjusting Ring (11) on the Nozzle (13).
Do not install the Lock Pin (12) at this time.
9.3.2 Examination
After assembly, examine the Nozzle (13) metal
seating surface. There must be no impairment
of the flat surface or the small radius on the
outer periphery of the Nozzle (13) which might
tear or score the O-ring (10E) or affect the
proper setting or sealing of the nozzle seat with
the O-ring (10E) in the Disc Assembly (10A-E).
It is not necessary to lap the metal Nozzle (13)
seating surface. However, it is important that
this surface be carefully protected to insure
against any damage due to handling.
9
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