The first tank that the compressed air enters is called the supply tank or
"wet tank" which comes from the fact it collects most of the moisture and
oil that drops out of the air.
If the moisture and oil that collects in the supply tank passes into the rest of the air brake system, it
can damage brake components and interfere with the operation of the system.
The following are some of the problems that can occur.
moisture and oil mixture can form a sludge that can pass from the tank into other components of the air brake system, damaging seals and causing brake
valves to stick.
The mixture of moisture and oil can become corrosive and damage the Air-tank and other system components.
Moisture in the brake
system can freeze in cold temperatures and may cause brake failure.
Too much moisture and oil collecting in the Air-tanks can reduce the volume of air
and may cause brake failure.
Key points to remember.
Air compressors are powered directly by the engine or by using belts and pulleys.
Air compressors are mounted directly on the engine or by
brackets and fasteners.
The governor controls the air compressor cut-in and cut-out pressure.
The operating pressure range for vehicle air brake systems
must be between 80 psi and 135 psi. It is unsafe to drive a vehicle when the air pressure is outside the normal operating range.
Compressed air is stored in the vehicle’s supply or "wet" tank and the dual service (primary and secondary) air tanks.
To prevent too much
moisture and oil from collecting, the air tanks must be drained regularly.
Air pressure gauges indicate air pressure in the vehicle’s dual service
(primary and secondary) air tanks.
Safety valves prevent over-pressure of the air brake system.
Low air pressure warning devices give drivers a
visual, and sometimes audible, warning that air-pressure is dangerously low.
An air dryer removes moisture from the air brake system and expels it when
the compressor reaches cut-out pressure.
An alcohol evaporator adds alcohol vapor to the air brake system to help prevent moisture in the system