Plast-O-Matic Series PRA 1/4 in. Poly Air Loaded Pressure Regulators w/ Viton Seals

1/4 in.
1.00 LBS

Call for pricing: (800) 333-3331

Designed for highly corrosive and ultra-pure chemicals, this pressure regulator uses compressed air to control pressure with greater accuracy as compared to standard spring-controlled models. Pressure regulators provide protection for valuable downstream instruments and filtration systems by converting fluctuating or excessive inlet pressure to a preset maximum downstream pressure. The PRA will routinely handle inlet pressure up to 150 PSI and accurately maintain a downstream pressure from 5 to 125 PSI. The design of the PRA features two opposing large area frictionless rolling diaphragms. Process pressure is applied to one of the diaphragms; air pressure is applied to the other. Because the air pressure can be maintained with more accuracy than the force provided by a spring, the PRA offers greater sensitivity and less variance from set pressure than any thermoplastic pressure regulator previously available. The PRA can be used in combination with Plast-O-Matic's patented Stabilizer which measures downstream liquid pressure and provides continuous feedback control for even greater sensitivity and performance.

Materials of Construction

Standard connections are female NPT threaded ports. Socket, flanged and spigot connections are also available. Standard body materials are Geon® Grade 1 Type 1 PVC, Natural Polypropylene, and Kynar® PVDF. Standard seal materials are Viton® and EPDM. External fasteners are stainless steel.


A relieving type air regulator is required to load the sensing port; see diagram. Series PRA pressure regulators prevent downstream pressure from exceeding the desired set pressure. Regulator will remain closed as long as set pressure is maintained. As equipment or valves downstream of the regulator begin to open and demand flow, the downstream pressure begins to fall and the regulator begins to open. As valves or equipment downstream open further, the pressure regulator continues to open until its maximum opening is reached. As the process is reversed, downstream pressure begins to increase and the regulator starts closing. When the downstream pressure again reaches set pressure the regulator closes bubble-tight. Like any pressure regulator, the PRA prevents downstream pressure from exceeding the set point. To "maintain" a specific downstream pressure, the PRA requires an additional control, such as the patented Series PRS Stabilizer.


  • Higher Flow Rates with Less Pressure Loss than competitive regulators!
  • Automatically regulates and prevents downstream pressure from exceeding its set point.
  • Wide range of adjustable settings from 5 to 125 PSI.
  • Rugged construction with inlet pressure to 150 PSI (10.34 bar).
  • Dual rolling diaphragm design assures sensitive operation.
  • Non-sticking design.
  • One-piece body and double u-cup design prevent leakage and eliminate "creep."
  • Patented Fail-Dry® safety vent warns of seal failure; permits valve to continue operating and prevents liquid/air contamination.