Appendix A - Technical Reference
150-504-100-03
40
August 1, 2002
HRE-504 List 1, List 1B, and List 2
Air Stem Valve
The air stem valve (ASV) is part of an all metal, nickel-plated brass assembly as shown in
. The
valve is used to pressurize the enclosure from an external air supply.
The assembly consists of an adapter that tightens into a brass fitting (located on the bottom of the base), the ASV
which tightens into this adapter, and a cap that screws on the top of the ASV. The adapter has two O rings that are
required to create an airtight seal. One is located on the outer threaded stem that connects to the brass fitting. The
other is located at the base of its inner well where it seals the ASV to the adapter.
To remove and replace the ASV:
1
Grip the adapter nut with a
3
/
4
-inch (1.9 cm) wrench, and the ASV with a 7/16-inch (1.1 cm) wrench.
2
While holding the adapter nut steady, remove the ASV by turning it counterclockwise. If the adapter nut
becomes loose, torque it to 60 inch-pounds.
3
Verify that the O ring in the adaptor’s inner well has remained in place. If not, reseat it.
4
Thread the new ASV into the adapter. Do not crossthread.
5
Grip the adapter nut with a
3
/
4
-inch (1.9 cm) wrench and the PRV with a 7/16-inch (1.1 cm) wrench and torque
the valve to 120 inch-pounds. Do not overtighten. Excessive torque does not improve the seal and may
damage the ASV.
6
Pressurize the chamber and check entire assembly for leaks.
Air Pressure Cutoff Valve
The air pressure cutoff valve (PCV) is part of an all metal, nickel-plated brass assembly as shown in
. The valve controls the flow of air from the air-core stub into the enclosure.
The assembly consists of an adjusting knob and stem that is interlocked to a limiting nut. The outer limiting nut
tightens into the outer threads of the body housing connected to the enclosure’s baseplate. The stem tightens into
the inner threads of the housing. The stem’s tip has three O rings that work to open and close the airflow through
the base of the body housing. When the adjusting nut is fully clockwise, the airflow is OFF. When it is rotated one
turn clockwise, the air flow is ON. The body housing also has an O ring on its threads to create an airtight seal
when the limiting nut is tight.
To remove and replace the PCV:
1
Loosen the limiting nut with a 1-inch (2.54 cm) wrench by turning it a half turn counterclockwise.
2
Since the valve stem is internally threaded to the body housing, both the limiting nut and adjustment knob
must be turned together. Turn them counterclockwise until both are fully unthreaded from the body housing.
3
Pull the adjusting knob and limiting nut subassembly away from the body housing until completely
disengaged. Some resistance will occur as the stem’s O rings rub against the walls of the body housing.
4
Check that the O ring is attached to the threaded tip of the body housing.
5
The replacement PCV assembly includes the limiting nut, adjustment knob and all O rings. Do not attempt to
disassemble it. Insert the valve stem into the body housing’s threaded tip. Insert it as far as it will go. Some
resistance will occur as the O rings contact the inner housing threads.
6
Rotate the limiting nut clockwise a half turn.
7
Tighten the adjusting nut to the O ring by grasping both the limiting nut and the adjustment knob and
tightening this subassembly into the housing. Do not crossthread.
8
Turn the adjusting knob clockwise until contact is felt between the stem’s O rings and the inner threads of the
body housing.
9
Use the 1-inch (2.54 cm) wrench to torque the limiting nut to 200 inch-pounds. Do not overtighten. Excessive
torque does not improve the seal and may damage the PCV.
Summary of Contents for 150-2202-01
Page 4: ...Inspecting the Shipment 150 504 100 03 iv August 1 2002 HRE 504 List 1 List 1B and List 2...
Page 8: ...List of Tables 150 504 100 03 viii Augusr 1 2002 HRE 504 List 1 List 1B and List 2...
Page 53: ...Appendix D Abbreviations 150 504 100 03 46 August 1 2002 HRE 504 List 1 List 1B and List 2...
