Pulsation and Surge Dampeners for Diaphragm Pumps

Why do I need a pulsation dampener for my diaphragm pump?

Positive displacement pumps, such as diaphragm or piston pumps, create pulsation due to its reciprocating nature of their stroking action. A wide range of pulsation dampeners are available to eliminate the pressure fluctuation which is precondition to get an uniform application during spray coating.

What is the difference between a ‘pulsation dampener’ and ‘surge suppressor’?

It is important to understand that there is a difference between ‘pulsation’ and ‘surge’.

Pulsation results from the acceleration and deceleration of the fluid caused by the action of a reciprocating pump. This can be eliminated by using a properly sized pulsation dampener, installed as close to the pump outlet as possible, which then moderates the pump’s pressure and volume fluctuations. Different designs are available, but the basic elements consist of a sphere pressure vessel containing a flexible diaphragm or bellow (e.g. made of PTFE, rubber, composite or silicone) which separates a gas (e.g. air or nitrogen) from the fluid in the lower chamber.

On the other hand, surge is a more irregular and less predictable pressure change which is caused by the fact that fluid systems never operate at constant pressure, for instance change of temperature, pumps are going on- and off-line, tank levels and rapidly closing valves. Surge suppressors are similar (sometimes identical) in design to pulsation dampeners, but are usually able to compensate larger pressure and volume fluctuations. One key difference to the pulsation dampener is the location where it is installed: although it can also be installed to the pump outlet, surge suppressors are commonly employed at various points throughout the fluid system.

What to consider when purchasing a pulsation dampener/surge suppressor?

Following main aspects have to be considered when purchasing a pulsation dampener or surge suppressor:

• discharge size of the pump, or system connections
• pressure range
• temperature range
• body and diaphragm material (based on the characteristics of the fluid to be pumped)

Where to install the pulsation dampener or surge suppressor?

As a rule-of-thumb: within 10 pipe diameters of the source of the pressure fluctuation.

What is a surge bottle?

A surge bottle (or surge chamber) is a simple reservoir that minimizes pressure fluctuations caused by the diaphragm or piston pump. It is a hollow metal pipe in bottle shape which is usually installed at the fluid outlet of the pump. Air trapped in this chamber compresses or expands according to changes in pressure of the pumped liquid. Compressing this air helps to minimize pressure variations.