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Back Pressure Regulator – 368 Series

The 386 Series Back Pressure Regulator is designed to control upstream pressure in low pressure gas piping systems.


The Varec Biogas 386 Series Back Pressure Regulator is intended for use in low pressure gas systems. It operates normally closed and will open when the upstream pressure reaches the regulator’s predetermined settings. It is typically used to control flow of gas to the flare.

The extensive range of sizes and its corrosion resistant 356 T6 aluminium construction allows its use in most applications encountered in the typical tank farm, liquid storage facility, landfill or waste water treatment plant.

The 386 Series Regulator utilises a large, spring loaded diaphragm, providing sensitivity while relieving excess gas with a minimal pressure drop. Set pressure is easily adjusted using the adjusting screw on top of the valve. An enclosed pointer provides quick visual indication of the set pressure.


Upstream pressure, sensed through the control line piping, is applied to the bottom of the diaphragm. The pressure acts against the diaphragm, causing the valve to open. As the pressure upstream of the valve rises, the diaphragm opens the valve, allowing greater flow capacity. As the pressure is relieved, the reduced pressure applied to the diaphragm allows the valve to close.

A 1/2” NPT connection is provided in the lower diaphragm housing for field installation of the sensing line. The line should be connected a minimum of 10 feet upstream of the regulator to avoid improper operation caused by turbulence, which may occur as the valve opens and closes.

If the regulator is installed indoors, the vent in the upper diaphragm housing should be extended outdoors with tubing. This will prevent gas from migrating into the room should the diaphragm develop a leak. A Varec 5200 Series Flame Check should be installed near the open end of the vent line for maximum protection.

Design Features:

  • Large Diaphragm for Sensitive Operation
  • Spring Loaded for Easy Adjustment
  • Corrosion Resistant Low Copper Aluminium Construction
  • Easily Adjustable Setting for Fine Tuning in the Field
  • Settings up to 20” WC (Consult Factory for Higher Settings)
  • Available in 2” – 12” (50mm – 300mm) Sizes
  • Three-way Solenoid Valve Option for Added Safety

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