Dispenser supply tank over 4,000 gallons water capacity or having a filling opening 1 1/4 inch or larger require a transfer bulkhead equipped with an emergency shutdown valve (ESV) for the vapor equalizing connection and an ESV for the liquid fill connection. A backflow check valve may be used for the liquid line if flow of liquid is limited to one direction.

Dispenser supply tank over 4,000 gallons water capacity or having a filling opening 1 1/4 inch or larger require a transfer bulkhead equipped with an emergency shutdown valve (ESV) for the vapor equalizing connection and an ESV for the liquid fill connection. A backflow check valve may be used for the liquid line if flow of liquid is limited to one direction.

• A. 1/2 inch
• B. 1 inch
• C. 1 1/4 inch
• D. 2 inches

Answer: (C)

The main idea is when a dispenser’s transfer bulkhead must have emergency shutdown valves on both the vapor equalizing line and the liquid fill line. The rule kicks in if the dispenser supply tank has a water capacity over 4,000 gallons or if the filling opening is 1 1/4 inch or larger. In that situation, you need ESVs on both the vapor and liquid connections to quickly shut off transfers and prevent spills or pressure issues during filling. A backflow check valve may be used on the liquid line if the liquid flow is limited to one direction, adding extra protection against reverse flow. From the options, the size that matches the triggering threshold is 1 1/4 inch. Smaller openings do not meet the requirement, while a larger size like 2 inches would also meet the condition, but the threshold specifically called out is 1 1/4 inch.

The main idea is when a dispenser’s transfer bulkhead must have emergency shutdown valves on both the vapor equalizing line and the liquid fill line. The rule kicks in if the dispenser supply tank has a water capacity over 4,000 gallons or if the filling opening is 1 1/4 inch or larger. In that situation, you need ESVs on both the vapor and liquid connections to quickly shut off transfers and prevent spills or pressure issues during filling. A backflow check valve may be used on the liquid line if the liquid flow is limited to one direction, adding extra protection against reverse flow.

From the options, the size that matches the triggering threshold is 1 1/4 inch. Smaller openings do not meet the requirement, while a larger size like 2 inches would also meet the condition, but the threshold specifically called out is 1 1/4 inch.