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19 September 2018

How to keep the pressure in your process constant

The design of an Equilibar® back pressure regulator

Equilibar® dome loaded back pressure regulators are used in a wide variety of applications. The body of the unit can be made from different materials. Inside the unit you can see its straight forward construction. A diaphragm sealed by two o-rings is placed between the main body and the reference cap. The back pressure regulator is placed downstream of a process to keep its pressure constant.

How to regulate your pressure

In this case, the process pressure is monitored by a pressure gauge. To set the pressure a standard manual forward pressure regulator is used. This forward pressure reducing regulator is connected to the reference port of the unit and sets the required pressure in the dome of the back pressure regulator. The back pressure regulator will hold the process pressure with a 1:1 ratio. Only when the process pressure exceeds the pressure set in the dome, will flow be released through the back pressure regulator. From the inside you can see the pressure being set on the reference port. The diaphragm seals the orifices and will only move when the upstream process pressure exceeds the reference pressure. The diaphragm will move without friction due to the force balance. When the flow is small, only a small part of one orifice will be used to release the pressure. When there is a rapid increase in pressure, the diaphragm will be pushed upwards, fully enabling the back pressure regulator to release a large amount of flow while maintaining the constant upstream pressure.


The multi-orifice design allows the unit to control the pressure with a stability better than 0,2% with a flow range of one to one hundred thousand in most research applications, which surpasses the performance of traditional back pressure designs.

Since the technology is scalable, Equilibar can cover a Kv range from 10e-11 up to 10 with a limited number of models. For high viscosities and vacuum applications even larger units up to 4 inch with a Kv value of 160 can be supplied.

Equilibar its patented back pressure regulators offer:

  • High precision
  • A regulator operates across very wide flow rate and pressure ranges
  • Respond extremely quickly to changing process conditions
  • Are compatible with highly aggressive chemicals
  • Can handle high temperatures
  • Are capable of regulating two phase flow
  • All regulators can be easily be automated with electronic pilot regulators

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