What is the minimum distance above the flood level of a fixture for an approved air gap?

An approved air gap is crucial in plumbing systems to prevent backflow and protect the water supply from contamination. The minimum distance that an air gap must maintain above the flood level of a fixture ensures that any possible overflow does not reach the potable water supply. The option indicating that the distance must be twice the diameter of the supply, but not less than 1 inch is correct because it aligns with plumbing safety standards that enforce proper separation to prevent contamination risks.

This rule ensures that even if there is a surge of water or a potential backflow event, the air gap is sufficient to allow for drainage without the risk of back-siphonage. The requirement for this minimum distance ensures that the water remains clean, meeting health and safety regulations mandated in plumbing codes.

Quantifying the air gap in relation to the diameter of the supply line helps standardize the measures across various plumbing installations, ensuring consistent safety practices. Thus, relying on both the diameter of the pipe and the minimum measurements plays a critical role in maintaining safe plumbing systems.