Glossary term

Reduced pressure zone (RPZ) valve

A mechanical backflow prevention assembly that uses two check valves with a differential-pressure relief valve to provide Category 4 protection against both back-pressure and back-siphonage.

Standards & Regulation

Double Check Valves

ED devices for Fluid Category 3 and the cases where they are no longer sufficient.

Pipework System Designs

Sizing, materials and isolation strategy for protected wholesome supplies.

RPZ Valves

Reduced pressure zone valves — installation, AIM, annual testing and Fluid Category 4 protection.

Filling Systems

Closed heating and chilled-water filling loops, Category 4 protection and RPZ vs break-tank choices.

Need help specifying?

Our technicians can walk the current risk, the required device, and the assembly that satisfies AIM.

Insight

Common RPZ installation failures we still see on site

Missing test cocks, inverted relief valves, and isolation that makes annual AIM testing impossible.

Insight

Filling loops on non-house systems: RPZ or break tank?

Closed heating and chilled circuits are Category 4. A double check on the filling point is not enough.

Insight

Specifying air gaps on Category 5 washdown

When a mechanical device cannot replace a Type A air gap — and how to dimension the weir.

Reduced pressure zone (RPZ) valve

Double Check Valves

Pipework System Designs

RPZ Valves

Filling Systems

Related articles

Common RPZ installation failures we still see on site

Filling loops on non-house systems: RPZ or break tank?

Specifying air gaps on Category 5 washdown

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