YOUR PUMP MAY LAST 3 TIMES LONGER
(Write this 12% down for your use in your size calculation).
Ancient pumps had large and heavy moving parts; the weight of these parts acted as a flywheel and evened out the driving power fluctuations. Today with lighter more compact and lower cost machines, there is less "flywheel effect". For example a good ammeter can detect more than a 50% electric power fluctuation between the suction and the discharge stroke of a duplex pump, despite the flywheel effect of the motor itself. If the torque of the pump shaft is measured, the torque fluctuation is typically 400% of the average. In other words there must be a large load
or force fluctuation.
The load fluctuations, which cause the power fluctuations mentioned above, cause the drive mechanism, belt, gear, and rods, to suffer huge repetitive stress reversals.
More than three quarters of the stress reversal may be avoided simply by the addition of an
"hydraulic cushion", "accumulator" or "pulse damper" to the piping system.
Reducing the system acceleration "head" pressure change that the piping volume imposes onto your pump, to say a maximum residual of 12% of the theoretical stead state condition, is generally adequate to achieve a tripling of pump fatigue life.
UNDERSTANDING FLOW OR PRESSURE PULSATION
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