I bought a used pancake compressor and just used it today. When I turned it
on, it reached it's peak level and turned off, which I know is normal. Upon
viewing the pressure gauge I saw it was dropping fairly quick. My hearing
isn't good, therefore, I asked the wife if she heard a leak and she did. I
pin pointed the air coming from a hole from the regulator valve which lies
under the cap. Therefore, my question, is this normal? I can't imagine it
being normal since it continuously turns my compressor on when it falls
below the set pressure. I tried turning the valve all the way in and air
still leaks. If this isn't normal, is it safe to assume I can replace it?
Thanks for all help.
It's pretty common for integrated tank-compressor-pressure switch units
to have a "switched leak" controlled by the pressure switch. You can
tell if your unit has this if the tube that connects the compressor
outlet to the tank inlet has a side tube that also goes to the pressure
switch, while the pressure switch is mounted on the tank to sense tank
pressure. The way this is *supposed* to work is this: when the pressure
switch detects low pressure in the tank, it turns on the motor and also
closes the "leak". The compressor pumps up the tank to the set
pressure, and the pressure switch shuts off the motor. At the same
time, it opens the little vent port to let the pressure in the
compressor outlet line bleed off. (There is a one-way check valve
between the outlet line and the tank that prevents the tank air from
leaking). This allows the compressor to start more easily next time,
since it's not instantly working against tank pressure.
Now, if you have a pressure switch with this bleeder arrangement, and
the check valve leaks, the air in the tank will leak away and the sound
of leaking will come from the vent on the pressure valve - but the
pressure valve is fine and the check valve is the problem.
On the other hand, if you don't have a vent as part of the pressure
switch, and air is leaking directly from the tank through the switch,
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