> On Tue, 13 Jan 2004, Karl Vacek wrote:
> > Compressors used with gas engines, and often high-hp electric
> > compressors as well, use unloader mechanisms. The engine or motor turns
> > the compressor over constantly, but when the system is up to pressure
> > the compressor stops compressing.
It's worth commenting that almost any air compressor will have some sort of
unloader mechanism, so that the motor does not have to start under load.
Mark Andy asked :
> Can unloaders be added to any compressor pump or must the compressor pump
> have been designed to accept them?
The kind that Karl described would normally be part of the compressor, but
there is no reason the unloader can't be installed in the line between the
compressor and the tank (with a check valve to hold the air in the tank).
In that case the compressor does still move air, but since it's all near
room pressure, the energy expenditure is minimal. However the unloader
valve (and the plumbing to it) has to be big enough to pass full compressor
output with little pressure rise.
Randall
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