A Type AUK1 air gap is a non-mechanical backflow prevention arrangement comprising of an interposed cistern fed via an inlet arrangement forming a Type AG air gap, and an outlet arrangement which discharges the contents by gravity into a separate receiving vessel. The receiving vessel (for example a WC pan or cistern) must be located a minimum distance below the interpose cistern. Depending on the outcome of an assessment by the local water undertaker can feed a single or multiple installations.
A Type AUK 1 air gap is rated by the Regulators as suitable backflow protection against back pressure risks no greater fluid category 3 and back siphonage risks up to and including fluid category 5.
A summary of some but not all of the requirements applicable to a Type AUK1 air gap is given below:
The interposed cistern must conform to the requirements for a Type AG air gap.
The maximum fluid level in the receiving vessel must be a minimum of 300 mm below the spillover level of the interposed cistern and invert (lowest point of flow which may be different to the lowest point of discharge) of the warning pipe.
The maximum fluid level in the receiving vessel must be a minimum of 15 mm below the lowest internal water level of the interposed cistern.
The fluid in the interposed cistern must be categorised as no greater than fluid category 3.
As it includes a Type AG air gap, Type AUK 1 installations should be inspected, and as necessary maintained every 12 months (BS EN 806: 5)
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