Location of relief valve from top of the tank?

Location of relief valve from top of the tank?

• A. Twelve inches
• B. Three inches
• C. Six inches from the top
• D. Nine inches

Answer: (C)

Relief devices need to vent the vapor space, not liquid, and there must be a small clearance from the top so normal liquid level changes don’t reach or cover the valve. Placing the relief valve six inches from the top gives a safe margin: it stays in the vapor space during heating and expansion, while avoiding direct exposure to splashing or liquid rise that could interfere with the valve’s operation. If it’s placed too close to the top, even a small rise or splash can reach the valve and cause issues; if it’s placed much deeper, rising liquid could near or submerge the valve, reducing venting effectiveness. So six inches from the top is the standard, best-fit distance.

Relief devices need to vent the vapor space, not liquid, and there must be a small clearance from the top so normal liquid level changes don’t reach or cover the valve. Placing the relief valve six inches from the top gives a safe margin: it stays in the vapor space during heating and expansion, while avoiding direct exposure to splashing or liquid rise that could interfere with the valve’s operation. If it’s placed too close to the top, even a small rise or splash can reach the valve and cause issues; if it’s placed much deeper, rising liquid could near or submerge the valve, reducing venting effectiveness. So six inches from the top is the standard, best-fit distance.