In a typical air gap, the gap must be how many times the diameter of the indirect waste pipe?

In a typical air gap, the gap must be how many times the diameter of the indirect waste pipe?

• A. One half the diameter of the indirect waste pipe
• B. The same as the diameter of the indirect waste pipe
• C. Two times the diameter of the indirect waste pipe
• D. Three times the diameter of the indirect waste pipe

Answer: (C)

A safe, reliable air gap starts with a distance that is at least twice the diameter of the indirect waste pipe. This scalable rule ensures a solid separation between the discharge end and the receiving drain, so backflow or back-siphonage can’t pull waste into the potable system under pressure changes. For example, with a 1-inch indirect waste pipe, the gap should be at least 2 inches; with a 2-inch pipe, at least 4 inches. A gap smaller than this (like half the diameter or equal to it) wouldn’t provide enough clearance to prevent backflow, while a gap larger than two times the diameter isn’t required for standard installations, though it may be used in special cases.

A safe, reliable air gap starts with a distance that is at least twice the diameter of the indirect waste pipe. This scalable rule ensures a solid separation between the discharge end and the receiving drain, so backflow or back-siphonage can’t pull waste into the potable system under pressure changes. For example, with a 1-inch indirect waste pipe, the gap should be at least 2 inches; with a 2-inch pipe, at least 4 inches. A gap smaller than this (like half the diameter or equal to it) wouldn’t provide enough clearance to prevent backflow, while a gap larger than two times the diameter isn’t required for standard installations, though it may be used in special cases.