Pre-Filling Pulsation Dampeners with Strut Valves

Pulsation Dampener Prefill

Many pulsation dampeners must have nitrogen, or in some specific cases air, prefill gas. Damper prefilling is done before pumping your liquid. The pre-fill cushion gas pressure will prevent the bladder / diaphragm / membrane from being damaged or ruptured. Pre-filling, sometimes called pre-charging, the pulsation dampeners is done through the stainless steel valve provided. The valve does not require any special tools; there is no tire valve pin core within. The valve is opened and closed with a ¾” (20mm) A/F wrench.

When all the results of fabrication have been flushed from the system, the test block has been removed from the piping base, the dampener is bolted in its place, and before liquid is pumped, you are ready to address pre-filling with nitrogen.

Establish the degree to which prefill pressure must be modified due to temperature. Cool nitrogen into a dampener than runs hot will need a lower prefill pressure because when it is hot the pressure rises. At a higher pre-fill pressure than pumping pressure, the dampener does nothing. Consider also that too low a pre-fill pressure effectively makes the dampener smaller and cause the membrane deflection to be greater, thus reducing lifespan.

To establish that the correct prefill pressure was chosen, and to monitor performance, do not use a gauge on the prefill valve / gas cushion. It is misleading because it tells little other than gauge response characteristics unless the pipe system is depressurized. Even then it will reflect temperature change. Pressure too high or too low can be misinterpreted. To determine performance use a rapid response pressure transducer and data capture at kilohertz taken from within the liquid system.

If you want to use a gauge, use one from your liquid system via a diaphragm seal or pressure instrument isolator.