Disassembly. Disassemble the drain valve
assembly only to the extent necessary to repair or
replace a defective parts or parts.
Remove two screws (5) attaching drain
valve (7) to mounting bracket (6).
Unscrew and remove tubing tee (1) from
drain valve (7).
Remove tubing tee (2), tubing adaptor
(4),and pipe plugs (3). Unscrew and
remove three cap screws (9), lock
washers (10), and separate cap (8) front
body (20). Remove spring (11).
Place a 1/8 inch diameter rod through hole
in side of body (20) and through hole in
valve stein to keep stem from turning and
remove locknut (13); then, remove rod.
Remove piston (12) and o-ring (14).
Unscrew and remove valve body screw
(15), tap on end of stem (17) to remove
seat (16) and valve stem (17). Remove o-
ring (18) and backup ring ( 19) from stem (
Cleaning. Refer to paragraph 6-3.a for general
Inspection. Refer to paragraph 6-3.b for general
Parts with dimensions listed in Table 6-1,
Table of Limits, shall be measured to
determine acceptability for repair and
Inspect valve spring for cracks. breaks,
and set. Refer to Table 6-2.
Inspect drain valve piston for nicks and
burrs that could cause sticking.
Inspect valve seat for nicks, burrs, or
Repair or Replacement. Refer to paragraph 6-
3.c for general repair or replacement instructions.
Replace all parts that are worn or
damaged to an extent that will impair their
Assembly. To assemble the drain valve
assembly, proceed as follows: (I) Assemble o-ring (18),
and backup ring ()19) on valve stem (17). Lubricate o-
ring with very light coating of clean compressor oil to aid
Assemble stem (17) into valve body (20)
and place a 1/8 inch diameter rod through
hole in side of body and hole in stem to
keep stem from turning when tightening
locknut (13). Assemble o-ring (14) on
piston (12), assemble piston in bore of
body over end of stem and secure with
locknut (13). Remove the 1/8 inch rod.
Assemble seat (16) and body screw (15)
in body (20). Attach mounting bracket (6)
to bottom of body (20) with screws (5),
positioned with mounting extension facing
side opposite tubing tee (2).
Assemble spring (11) and cap (8). Secure
cap to body with lock washers (10) and
cap screws (9).
Install pipe plugs (3), tubing adaptor (4),
and tubing tee (2). Position tubing tee (2)
with run of tee horizontal with respect to
Use a wrench to hold body screw ( 5) and
install tubing tee (1) into body screw with
run of tubing tee (1) parallel with the run of
tubing tee (2).
Attach mounting plate (6) to compressor
frame using mounting nuts, flat washers
and mounting screws.
Unloader Control Box Group (See Figure 8-28).
The following paragraphs contain disassembly, cleaning,
inspection, repair or replacement, and assembly
instructions for the unloader control box group.
Disassembly. Disassemble the unloader control
box group only -to the extent necessary to repair or
replace a defective part or parts.
Remove nuts (7), lock washers (8), flat
washers (9), five insulator washers (10),
and machine screws (11). Remove plug
Remove nuts (1) and washers (2) from
control box mounts (3). Replace washers
and nuts after box is removed.