Technical data

4.5 CLEANING AND MAINTENANCE.
Proper maintenance of spray guns is necessary to preserve the
life of the gun and ensure high quality results. The gun
requires little other maintenance if kept clean.
a. Basic maintenance consists of occasional lubrication.
The packing surrounding the air valve stem shall receive
a few drops of light oil to maintain easy movement of
the air valve. The packing enclosed in the packing nut
around the fluid needle shall be lubricated for easy
movement of the fluid needle assembly. The spring for
the fluid needle assembly shall be coated with petrola-
tum per VV-P-236 (Vaseline®). In addition to lubrica-
tion, parts that experience wear, such as air nozzles,
fluid nozzles, and needle assemblies, should be periodi-
cally replaced.
NOTE
Excessive tightening of the packing nut will
damage the packing and the needle valve
assembly.
b. After each paint job, the gun shall be thoroughly cleaned
with thinners/solvents listed in Paragraph 4.6. If clean-
ing is delayed, the time needed to clean the gun is
greater, and there is a potential for damage to the
equipment.
When using solvents, keep away from heat and
open flame, keep container closed, use only with
adequate ventilation, and use gloves to avoid skin
contact.
(1) To clean a siphon-feed gun, unscrew the air cap and
release the paint cup from around the siphon tube at
least a distance of 1 or 2 inches. Hold a cloth over the
air cap and trigger the gun. Air will be sent into the
passageways, forcing any excess paint back down
the siphon tube and into the loosened paint cup.
(2) Remove the paint container and clean the inside
using MIL-T-81772, Type I or II thinner or TT-T-
2935 purging thinner or one of the lower vapor
pressure solvents listed as preferred alternatives for
these in Paragraph 4.6.
Abrasive materials and chemical strippers shall
not be used to clean spray gun parts, as damage to
the gun will result.
(3) Fill a quarter of the clean container/cup with the
same type of thinner or solvent (fresh/unused) used
to clean it.
(4) Remove the air nozzle and carefully lower it into the
container/cup of thinner or solvent.
(5) Using a nonmetallic bristle brush, clean the fluid
nozzle openings and other parts of the gun that are
difficult to reach, such as around the packing nuts
and controls.
Do not submerge the gun in thinner or solvent as
they can dry out the packing around the fluid and
air stems.
(6) Dampen a rag with thinner or solvent and wipe the
entire gun and cup until they are free of paint.
(7) Using the bristle brush clean the air nozzle and its
openings.
(8) Put the gun back together, and spray clean MIL-T-
81772, Type I thinner only through the gun until a
fan of clear thinner is produced. Do not use the lower
vapor pressure solvents listed in Paragraph 4.6 for
this final flushing procedure for the same reasons
noted in the CAUTION in Paragraph 4.6.
(9) Remove any excessive thinner, and wipe the cup and
gun with a clean dry rag.
NOTE
A spray gun contains parts that must work to-
gether. Dismantling a spray gun after each paint
operation will cause excessive damage to the gun
and its seals. A spray gun should only be dis-
mantled when a proper spray pattern cannot be
produced.
TO 1-1-8
4-22