Question 77

The minimum air gap for backflow protection for a lavatory with a spout opening 3 inches away from the nearest wall is 1 inch.

To ensure adequate backflow protection, the minimum air gap required is 1 inch. This distance is necessary to prevent any potential contamination of the water supply.

A) 1/2 inch

A 1/2 inch air gap is insufficient for backflow protection according to plumbing codes. The minimum requirement is designed to provide a greater buffer against potential contaminants entering the water supply, which would not be achieved with just a 1/2 inch gap.

B) 1 inch

A 1 inch air gap is the correct answer as it meets the minimum requirement for backflow protection. This distance provides a sufficient barrier to prevent contaminants from being siphoned back into the potable water supply, ensuring safe water delivery.

C) 1 1/2 inches

While a 1 1/2 inch air gap exceeds the minimum requirement, it is not necessary for backflow protection in this scenario. The regulations specify that 1 inch is adequate, making this option unnecessarily large.

D) 3 inches

A 3 inch air gap is excessive as the minimum requirement is only 1 inch. Although it does provide backflow protection, it is not practical or required for the situation described and may lead to inefficient use of space.

Conclusion

The minimum air gap for backflow protection is definitively 1 inch, making option B the correct choice. All other options either fail to meet the requirement or exceed it unnecessarily, demonstrating that only a 1 inch air gap is appropriate for effective and practical backflow prevention in this context.