Glossary term

Category 1–5

Five fluid risk classes in BS EN 1717 / Schedule 2. Category 1 is wholesome water; Category 5 is a serious health hazard (pathogenic organisms).

Standards & Regulation

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

Sizing, materials and isolation strategy for protected wholesome supplies.

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

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

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

Insight

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

Insight

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

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