Tool

Air gap sizing tool

Determine minimum Type A and Type B air gap dimensions per BS EN 1717.

Recommended protection device

Enter values and calculate to see a recommendation with the supporting regulation citation.

How to use this tool

STEP

Type A (unrestricted) or Type B (weir overflow) per BS EN 1717.

STEP

Use the bore of the incoming pipe, not the vessel.

STEP

The result is the unobstructed vertical distance above spillover.

Regulation guide

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.