How to select pressure regulators?

Pressure regulator selection

When you select a pressure regulator for your application, consult the flow curve, not the Cv  to make sure the regulator performance is according the actual flow and pressure. To size the right pressure regulator did you check if it is the right pressure you will set your regulator to? Are you considering the right units? Is it the right inlet pressure range? Do you need to calculate any other factors if your system medium is not a fluid but a gas?

If you have answered these questions then you can start reading the flow curve.  Based in that range of flows, the curve will tell you what pressures the regulator is able to control. The pressure regulator will perform most consistently along the parts of that curve . You want to avoid operating the regulator on the ends of the curve where non ideal conditions can occur like creep (seat leakage by contamination) and droop (drop in outlet pressure by increased flow, mainly caused by the changes in the force of the spring when is stretches). Convince yourself the outlet presusre can be reached at a certain flow and inlet pressure to select the correct type of pressure regulator. In Product Gauge the specific product information including flow curves can be found in the supplier product catalog.

Dos and Don'ts using a pressure regulator

  • Pressure regulators are not “Safety Accessories” such as safety relief valves as mentioned in the Pressure Equipment Directive 97/23/EC.  Also pressure regulators should not be used as a shutoff valves, as they are designed for precision upstream pressure control.

  • A safety relief valve is designed to protect downstream personnel and equipment should over-pressurization take place. As such, when it’s set pressure is overcome, it will blow wide open immediately and exhaust all of pressure. It needs to be able to handle the full flow
of the system in order to rapidly exhaust to protect downstream apparatus.

  • Install a pressure relief valve at the downstream line from the regulator to protect the downstream equipment and low pressure (P2) side and sensing element of the pressure regulator from over pressure.

  • Self-venting and captured-venting pressure regulators can release system fluid to the atmosphere, do not expect to release a full system capacity, better use a vent valve in the downstream line connected to a vent line.

  • Position the self-vent hole or the captured vent connection always away from operating staff.

  • Avoid the installation of a pressure regulator close to pressure pulsating equipment like pumps to avoid damage of the regulator internals.

  • A particle filter should be installed before the inlet of the pressure regulator to avoid seat-leakage by contamination.

Pressure control instrument categories