Surge problems with reciprocating, single diaphram pumps 1

[gpl20]

Currently experiencing severe surging from a Milton Roy single diaphram pump system, despite having a pulsation dampener installed.

The dampener is 300mm downstream of the pump after a T-piece fitting for a pressure gauge but upstream of any other equipment. Pressure gauge isntalled to check discharge pressure of pump (and check regulator working)

System is on a 15mm line, and also includes a safety relief valve and a regulator downstream of the dampener, then expands to a 25mm line.

All mechanical issues have been exhausted. all equipment is technically sound, dampener is charged correctly (and isn't leaking, membrane hasn't been breached), regulator set correctly, pump working (mechanically) "well".

Surging is so severe that it causes pressure gauges and flow meters to "shake" apart within days, weeks at the most.

Any ideas on possible causes / solutions greatly appreciated.

 

[Guidoo]

From your question I get the impression that you have problems with excessive pressure pulsations leading to piping vibration. This is the result of the interaction between the flow variation of the pump and the acoustic natural frequency of the piping.

In order to avoid this, a pulsation analysis and acoustistical evaluation of the piping system should be done.

According to the Cameron Hydraulic Data Book:

"Once determined, the acoustic frequency of the piping system has to be separated or removed from the excitation frequency by the pump's normal flow variation. Typically, pulsation dampeners or stabilizers are installed to generate this separation. Pulsations suppression devices change the acoustic characteristics of the system.

Unfortunately, on e cannot indiscriminately install pulsation dampeners and expect reliable results. If the proper selection techniques are not followed, the addition of a dampener could increase system problems instead of reducing or eliminating them."

So my conclusion is: You will have to do a pulsation/vibration study to select proper dampener.

 

[jmw]

A good site for sourcing and understanding pulsation is:

http://www.pulsation-shock.com/

JMW

http://www.viscoanalyser.com

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