a. Install pressure relief valve in test set-up as
4.8.6
INSTALLATION, Install a new tube fitting
illustrated schematically In Figure 4-3. Be sure to
gasket(5-5, 12)in the groove at the root of the valve
observe dimensions specified for approach and exit
body mounting boss. Screw the pressure relief valve
sections.
into its appropriate mounting port, making sure the joint
b. Close bleed valve. Adjust pressure regulator to
is air tight.
apply a gradually increasing air pressure to approach
4.9 SAFETY FITTING ASSEMBLY
section Relief valve should open (i. e., air flow from
leakage tube exceed three cubic centimeters per hour)
4.9.1 REMOVAL
The safety fitting assembly is
before applied pressure reaches 3600 psig.
mounted in the tee fitting installed at the inlet of the air
receiver (see Figure 1-4). To remove the safety fitting
c. If relief valve fails to open, remove collector
assembly (see Figure 5-3):
cup, adjust stem of valve a small amount, replace
a. Disconnect valve-to-safety-fitting connecting
collector cup, and repeat test.
Repeat alternate
tube (54) from safety fitting assembly.
adjustments and tests until relief valve opens, as
indicated by a minimum air flow of two scfm, with an
b. Back off nut (57) and unscrew safety fitting
approach section pressure of 3600 psig maximum.
assembly from union (58).
d. Close pressure regulator and open bleed valve
slightly to slowly relieve air pressure in approach section
4.9.2 DISASSEMBLY. Disassemble the safety fitting
Pressure relief valve should close (reseal) before
assembly in accordance with the exploded view Figure
approach section pressure drops below 3200 psi as
5-8.
indicated by pressure gage.
4.9.3 CLEANING AND INSPECTING PARTS. Clean
e. Repeat procedure of steps b, c and d. If
and Inspect the parts of the safety fitting assembly as
required relief valve operation cannot be obtained by
follows:
adjusting stem, change setting of adjusting screw
a. Wash all parts In dry-cleaning solvent(Federal
installed in valve body, and repeat complete test and
Specification P-S-661) and dry thoroughly with clean,
adjustment procedure. Final setting of adjusting screw
lint-free cloths. Use filtered, compressed air to blow all
and stem must allow installation of 0.025 inch diameter
residue from bore of fitting housing.
stainless steel safety wire and lead seal as in original
valve configuration
b. Inspect parts for damaged screw threads,
cracks, and other indications of deterioration. Discard
f. Close pressure regulator, open bleed valve to
damaged and questionable parts.
relieve air pressure In test set-up and disconnect
pressure relief valve from test equipment.
Figure 4-3. Set-up for Testing High Pressure Relief Valve
30
