it a challenge to absorb the pressure pulsations flowing through it. A specialized
hydraulic muffler is needed to reduce the
effects of hydraulic force.
“A fundamental thing in engineering
is energy conservation,” Dotti said. “If
you don’t do something with the released
energy, it’s just going to go someplace
else. Hydraulic mufflers have cavities
that hydraulic fluid flows in and out of
to get viscous flow. That action sucks up
energy without impeding flow. It takes
the energy that’s in the form of pressure
pulsations out of the system.”
A Parker Hannifin Inline Pulse-Tone
hydraulic shock suppressor was installed
on the discharge/outlet side of the food
processing plant’s hydraulic pump to
stop pulsations and resulting noise before
it traveled through the piping and radi-
ated off of other structural components.
The conference room experienced a sig-
nificant 20 dBA noise reduction, lower-
ing the noise “loudness” by four times.
As shown in figure 1, hydraulic fluid
flowing into the Pulse-Tone goes through
three different baffles or diffusers. These
metal baffles are designed to convert
1/2” diameter holes to 1/32” diameter
holes. The total radial distance through
these baffles is only 1/4”.
After passing through the holes, pulsations strike a nitrogen-charged rubber
bladder. The bladder deflects each time
it’s hit by a pulsation. This slight bladder
deflection reduces the shock and noise
by absorbing the pressure pulse.
Overall, the large area of the bladder,
with its ability to oscillate at a high
frequency, and the short distance each
pulsation has to travel once it enters the
unit, are key performance features allowing the Pulse-Tone to reduce sound and
shock in factory environments.
This sound phenomenon helps
explain why many pump manufacturers
list a very low dB rating, but when the
pump is installed on a power unit, the
resulting sound level is much higher.
In fact, it’s almost impossible to forecast how much additional sound the
hydraulic lines and surrounding structure will radiate.
A hydraulic shock suppressor
reduces pump pulsations and shock.
Decreasing these pulsations and vibra-
tions not only reduces noise levels,
but helps to prevent primary causes
of component wear and leakage. This
allows power units with an Inline
Pulse-Tone to operate at higher RPMs
with smaller, less expensive compo-
nents and, most importantly for the
food processing plant, less noise.
For more information, contact Parker
Hannifin’s Accumulator & Cooler
Division at 815-636-4100.