Liquid Dynamics
Pulsation Analysis, Diagnostics, Prediction by Software
Pipeline and Pump user Problem -

Pulsation Analysis, Diagnostics, Prediction by Software

LIQUID DYNAMICS Ltd. offer Pulsation / Vibraton and Shock - Analysis & Diagnostics + Software Models
Please call toll free USA 1-888-326-7377 WE HAVE PEOPLE - Not voice mail. --44-161-480-9625 UK
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Head loss, surge
Friction losses
Volume inefficiency
Velocity jump shock
Frequency vs. Pipe ID


LDi Catalog Printable PDF45

ALLOW FOR "OVERLAP" of one displacement to the next.
This is dependent on the volumetric efficiency,
due to compressibility of your system liquid.

This may radically effect the level of flow fluctuation, and pressure pulsation.

If in this example, left, the pump was a triplex then the flow would come to a complete halt between strokes. This is because a rotary driven reciprocating pump sucks & discharges for 180° of rotation and the next displacement begins after 120°. The overlap on triplex at 100% efficiency is therefore 60°. At 77.512% the calculation shows that the 60° has been lost, hence with no overlap the flow will come to a halt between displacements. It will be as "pulsatious" as a duplex.

By the same calculation as the example; if the efficiency was 85% then the lost angle would become 48°. With a "Quin" a new displacement should begin every 72 degrees (360/5), and as discussed above a triplex should displace every 120°. 120° minus 72°=48°. But at 85% efficiency, 48 has been lost, so a Quin can cause as much flow fluctuation as a perfect Triplex if the quin has low volumetric efficiency.
THEREFORE, A three headed diaphragm metering pump may produce flow fluctuations as bad as, or worse than, a duplex pump or double acting simplex pump.
A quintuplex, or 5 plunger pump, may produce flow fluctuations as good as, or worse than, a good triplex pump, it all depends on volumetric efficiency.
Consequenty, where N(squared) is a divisor, you would have to treat a triplex N(squared) as 2x2=4, not 3x3=9.
Phone USA 910.270.2737
PO Box 506 Hampstead, NC 28443 USA
UK (for EC) --44(0)161-480-9625
PO Box 47, Stockport, UK SK3-OLH


Liquid Dynamics International provides pipeline and pump user problem analysis, diagnostics, prediction by software, pulsation analysis, piping system analysis, and piping system simulation. For water hammer and shock solutions pulsation dampening and shock alleviating devices can be obtained from our associate websites:

PulseGuard Inc., and Ltd. for further information about pulsation dampeners / pulsation dampers. - Pulsation Dampener - Pulsation Dampeners - Pulsation Dampers
PulseGuard für Deutschland - Pulsationsdämpfer and to find large gas bag vessels, jumbo bladders, float separator / big bellows type pipeline shock attenuators and expansion / contraction volume compensators, surge alleviators, and shock alleviators. - Surge Alleviators - Shock Alleviators and for information about energy saving in pumping systems, standby emergency power, safety shutdown systems, hydraulic accumulators, and hydropneumatic accumulators. - Hydraulic Accumulators - Hydropneumatic Accumulators to find protection against excess flow. Guard against toxic spills when pipes burst, guard against gushers and fluid loss when hoses split, Flow-Guard guards against excess flow floods with flow fuses and breather bags
Flow-Guard - Flow Fuses and Breather Bags

Liquid Dynamics