Unlike traditional pressure reducing regulators that open to increase pressure, these relieving-type or backpressure-type regulators open up to reduce pressure.
Equilibar’s relieving back pressure regulators are dome-loaded and use a 1:1 air pilot pressure on their dome to communicate the set-point. The set-point signal can be communicated by either manual or electro-pneumatic pilot regulator.
Relieving pressure regulators are available in a wide range of sizes:
- 1/4″ to 1″ – GS Series back pressure regulators
- 1.5″ to 4″ – BD Series back pressure valves
- 4″ to 6″ – HV Series back pressure valves
The following chart illustrates the ability of the Equilibar back pressure regulator to control in the range of 3 inWC (inches of H2O).
Pilot Regulator Options for Low Pressure Control
Manual Control | Computer Control | |||
Product | LPR2 | QPV | ||
in H2O | millibar(g) | in H2O | millibar(g) | |
Lowest Pressure Range | 0.5 to 7 | .75 to 17 | 0 – 4 | 0 – 10 |
Sensitivity | 0.02 | 0.05 | 0.01 | 0.03 |
Other Pressure Ranges | 1 – 10 1 – 28 | 2.5 – 25 2.5 – 70 | 1 – 10 1 – 28 | 2.5 – 25 2.5 – 70 |
Selected Applications for Low Pressure Relieving Valves
Application | Schematic |
Pressure Regulator for Tank Blanketing or Padding | ![]() |
Controlling Pressure in an Extrusion | ![]() |
Protecting Rupture Discs using Back Pressure Regulators | ![]() |
Simulating Changes in Altitude using Equilibar Vacuum Regulators | ![]() altitude simulation chamber pressure control |
Controlling Pressure Referenced to Absolute Pressure Units | |

The Equilibar back pressure regulator relieves flow to control pressure. It has a 1:1 dome-loaded design, and can be piloted by either a manual or electronic pressure regulator

Relieving back pressure regulator can be used to control liquids or gases in the very low pressure range. Shown with precision electronic pressure regulator

The Equilbar HV32 relieving back pressure regulator is available in 2″, 4″, and 6″ sizes for precise low pressure control at high flow rates