Refrigerating Specialties Division
2
DISASSEMBLY & ASSEMBLY
Refer to the exploded view (Fig. 1) for parts
discussed in this section.
Before disassembling or assembling any A4A type
regulator, read the information in this bulletin and
Bulletin RSB, Safety Procedures for Refrigerating
Specialties Division Refrigeration Control Valves.
Before a regulator is removed from the line or
disassembled in the line, make sure that all
refrigerant has been removed from the regulator,
including the bonnet where applicable, and the
close-coupled strainer. The regulator must be
isolated from the rest of the system in a safe manner.
When pumping down to remove the refrigerant the
manual opening stem 33A must be turned all the
way out (counter-clockwise) to make sure the valve
is open.
ALL A4A REGULATORS
GENERAL PROCEDURE
The construction of the regulator and the method
of disassembly are relatively simple, but some
procedures must be followed to avoid damage. The
following describes the procedure for the basic A4A;
special instructions for other styles will be included
in other appropriate sections.
Disassembly - Take care when removing Seal Caps
1 and 44 in case some refrigerant may be trapped
inside. Back the Adjusting Stem 6 all the way out to
remove any pressure from Range Spring 13
otherwise damage to Diaphragm 17 or Pilot Seat
18 may occur. Remove Bonnet 8 by carefully
removing Cap Screws 11. Take care not to damage
Diaphragm Follower 15. Remove Adapter 28 by
removing Cap Screws 31. Turn the Manual Opening
Stem 33A all the way in until the flats on the stem
barely protrude from the stuffing box nut. Push
Piston 30 down against the spring force. The piston
should move freely down and be returned by the
spring force. If the piston is jammed or sticky, remove
Bottom Cap Assembly which includes Items 33
through 42 by removing Cap Screws 39 or
unscrewing Bottom Cap, 20mm through 32mm
(3/4" through 1-1/4"). Using a hard wood dowel rod
inserted through the bottom of the valve, tap the
piston upward and out. Thoroughly clean all parts.
If jamming has taken place and the piston and bore
are scored, remove all burrs by polishing the piston,
bore and throttling plug with fine crocus cloth.
Inspect the seating area of the Throttling Plug 33
for damage or erosion. If damaged it should be
replaced. It would be advisable to replace the entire
bottom cap assembly. Inspect all gaskets and "O"
rings for damage and replace where necessary.
Assembly - When reassembling the valve, all
internal parts should be clean, dry and lightly oiled
with refrigerant oil, except “O” rings. Apply silicone
grease to the “O” rings. Care must be taken
especially when the parts are cold since moisture
can condense on parts and cause rapid rusting.
When replacing gaskets, they should be oiled very
lightly with refrigerant oil before assembly. Install
bottom cap assembly first and tighten in place.
Carefully replace the piston; never try to force it in
place. Align the Adapter Gasket 29 carefully with
the proper holes in the adapter and valve body and
fasten adapter in place. Before assembling the
bonnet be sure the Adjusting Stem 6 is turned all
the way out and that the Bonnet 8 and Diaphragm
Follower 15 are properly aligned, otherwise damage
A4A, A4AK, A4AL, A4AE, A4AO
FIG. 1
