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Relief, By Pass, Back Pressure and Anti-Siphon Control Valves

Angle and in-line valve designs

Perfect for corrosive chemicals, water and ultra-pure liquids, Plastomatic series of relief valves features a solid, nonsticking PTFE shaft passing through three U-cup seals with a proven, high performance relief valve providing rugged dependability for acids and other highly corrosive liquids. True Blue ® Relief Valves provide smooth, sensitive operation to help you manage pressure “upstream” of the valve.


This valve design serves many functions:

  • Preventing overpressure conditions in vessels and piping systems (relief valve).
  • Providing by-pass flow relief to avoid pumping problems such as deadheading (pump bypass valve).
  • Maintain backpressure in a piping system (backpressure regulator).
  • Enhance pump performance by maintaining backpressure on the pump outlet (pump backpressure valve).
  • Prevent gravity-induced siphoning through a pump, opening only when the pump is on (anti-siphon valve).
  • NEW! Series TRVDT 3-port design…the features of our state-approved RVDT now in a 3-way valve!

And provides many outstanding features:

  • Offer wide range of pressure settings with sensitive operation.
  • Provide smooth operation with higher flow.
  • Fail-Dry safety feature (not available on RVD or RVTX).
  • Each valve is individually tested prior to shipment.
  • No wetted metals; all external fasteners are stainless steel.
  • Maintenance-free designs.
  • Designs for crystallizing liquids.
  • Designs with no wetted elastomers for ultra-pure chemicals and water.
  • Non-contaminating PTFE diaphragm designs.
  • Factory pre-set if requested.
  • Tamper-proof option.

What is a Relief valve?

All Relief Valve styles are normally-closed and provide relief from excess/dangerous pressure for closed-top vessels or piping systems, these normally-closed valves provide system control benefits from over-pressure and/or pressure surges. Relief Valves begin to operate once the set inlet pressure is reached and liquid will begin to trickle through, if this pressure increases the valve opens further allowing more flow.

What is a Bypass valve?

A Bypass Valve is a normally closed valve set within a bypass line which is used to divert a proportion or all of the flow to safeguard equipment. Typically used to divert flow to prevent centrifugal pumps from “dead heading” or running dry.

What is a Back Pressure valve?

A Back Pressure valve is a normally-closed regulator installed at the END of a piping system or after pressure sensitive equipment to provide an obstruction to flow and thereby regulate upstream (back) pressure. A Back Pressure valve is called upon to provide pressure in order to draw fluid off the system.

What is an Anti-Siphon valve?

An Anti-Siphon Control valve is used to prevent unwanted chemical siphoning through a pump, when negative pressure at a lower elevation could create a siphon and drain a tank. The valve is pre-set to open at the desired pumping pressure, but seals tightly when the pump is shut off and a vacuum occurs downstream.

Enquire about this product

Send a message to the Chem Resist sales team for more information.

Alternatively, contact us on +44 1924 499466 or [email protected].

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