f. Unloader Valve. The unloader valve is used to relieve pressure from the
compressor head during initial start up.
(1) This valve is also used in the drying cycle to discharge stored air to the
atmosphere, thus regenerating the desiccant.
The unloader valve is mounted to the pressure switch housing.
The main function is to reduce noise during the purging cycle.
(2) The other purpose or function is to keep contaminants out of the
compressor when there is no pressure in the line keeping the unloader valve closed.
h. Pressure Switch. The pressure switch controls the maximum and minimum
pressure that the M5A compressor delivers.
(1) The pressure switch has a rubber diaphragm that flexes due to the
storage tank pressure.
There are high and low settings that you can adjust.
The pressure switch is factory preset at 80 psi and 60 psi respectively.
(a) At the high pressure setting (80 psi), the motor that controls the
compressor is turned off. Also, the unloader valve is depressed and the compressor
begins its drying cycle.
(b) At the low setting (60 psi), the compressor motor energizes, and
the unloader valve is allowed to close. This occurs because the tab that had depressed
it at the high setting is no longer pushed forward.
i. Cooling Coil. The cooling coil is a piece of copper tubing that is coiled. The
muffin fan forces air over this coil to cool the air before it reaches the drying chamber on
its way to the storage tank.
j. Intake Silencer. The intake silencer is a dry type filter used to remove
contaminants from the atmosphere at the intake of the compressor. The silencer:
Must be on the compressor and not damaged before you start the
Reduces the noise created during the suction stroke of the air