TM 5-4220-225-14
c. Relief Valve Test (figure 2-4).
CAUTION
Ensure test set regulator (1)is turned fully counterclockwise before any tests are
performed.
NOTE
The relief valve test is intended as a premission tests, unless the relief valve is suspect.
*(1) Remove the helmet air supply adapter cap and gasket and install the air supply whip (1).
*(2) Connect air supply, with pressure gage, to air supply whip (1).
(3) Remove the air supply diffuser assembly (2) and install the test plug in the diffuser adapter (3).
(4) Open air supply valve (4).
(5) Slowly apply supply air and check pressure gage ready when relief valve (5) cracks (opens).
NOTE
The relief valve is set to 15 psig.
(6) If cracking pressure is improper, notify your supervisor.
(7) Slowly remove air supply air.
(8) Watch and listen for the relief valve (5) to seat, approximately 90 percent of cracking pressure (18 psig).
(9) Remove air supply air completely.
(10) Remove air supply from air supply whip (1).
(11) Install protective cover and gasket.
(12) Remove the diffuser test plug and reinstall the air supply diffuser assembly (2).
(13) Stow all equipment and tools.
2-20
