Ergonomics - Atlas Copco

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This is done with a minimum increase of
pressure drop, irrespective of air flow.
Another advantage of this design is the
reduction of stop noise. When the grinder is
stopped the air flow rapidly decreases.
A conventional muffler will lose the pres-
sure drop in the restriction and most of its
damping performance. The grinding wheel
with its stored rotational energy will take a
few seconds to stop. During this period the
motor is actually sucking air through the
outlet and generating a lot of noise. The pis-
An oil cushion eliminates high-frequency noise from the process.
ton in the new design shuts the outlet and
there is no stop noise.
For nutrunners and other machines
which only work for short periods at a time,
it is more efficient to fill the muffler with
cellular materials that break up the currents
in the air stream, thus reducing noise levels.
Aerodynamic noise
The pressure drop in the outlet of the muf-
fler will accelerate the air and increase its
velocity. Sound power generated is a func-