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About the GS3 series back pressure regulators

Cv: 1·E-03 to 1.80  |  Max. Temperature: 300°C  |  Max. Pressure: 172 bar (2500 PSI)


The GS3 series consists of the GSD3, GSDM3 and GSDH3 units. These GSD3 units have some overlap with the Equilibar® research series and are a bit larger than the GSD2 units. The unit has a diameter of only 89 mm and a maximum Cv value of 1,8. Furthermore, the rangeability of the regulator is so large that it is hard to oversize it. With a polymeric diaphragm, the minimum Cv value is 10E-3.

Customers use the GSD3 units of Equilibar for liquid, gas and two-phase flow applications. The most common applications are fuel pump testing in the automotive industry, pilot plant scale catalytic research applications and fuel cell testing. All other applications where you need a wide rangeability, excellent stability and a robust design are also common. In some low-flow research applications, you need a high Cv because of the high viscosity of the media. High viscosity flow control can be very challenging for standard control valves. The construction of the regulator allows stable back pressure control without unwanted increase in pressure drop when increasing the flow. Especially relevant is our video, where you can see how it works on our back pressure regulators page.

If you combine the unit with an absolute electronic pressure regulator, you can easily turn the back pressure regulator into a vacuum controller. In a vacuum, the sizing of traditional control valves becomes very important because the volume flow will increase rapidly when you reduce the pressure. If you need to vary the flow as well, you require a control valve with a very large rangeability. Equilibar valves can deliver this rangeability because the construction contains not one but a very large number of orifices that can open when you need it.


Equilibar back pressure regulators can be made in a wide variety of materials. Standard, they are available in SS316L, but Hastelloy is very common as well. More exotic alloys like Monel 400 or Zirconium are available on request. For low pressure or vacuum applications, you can use Anodized Alumina units or some aggressive media like full PTFE or PVDF units.

While the standard GSD3 is able to withstand 34,5 bar (500 PSI), the GSDM3 and GSDH3 are available for 82 bar gauge (1200 PSI) and 172 bar gauge (2500 PSI). These units are a bit larger and thicker than the 34,5 bar gauge (500 PSI) version.

Larger flow rates with a process connection up to 1″ with a Cv-value up to 10 are available in this General Service series.

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The working of an Equilibar Dome Loaded Back Pressure Regulator

How to Rebuild your Equilibar Back Pressure Regulator

Different materials that are used to make Equilibar Back Pressure Regulators and diaphragms