In a one-pipe steam system, the supply pipe must have a minimum diameter of how many inches?

In a one-pipe steam system, the supply pipe must have a minimum diameter of how many inches?

• A. 1 inch
• B. 2 inches
• C. 3 inches
• D. 1.5 inches

Answer: (B)

In a one-pipe steam system, the supply line must be large enough to deliver enough steam to all radiators and keep condensate from blocking the line. A minimum of two inches provides sufficient cross-sectional area so steam can flow with a manageable velocity, reducing pressure drop along the main and minimizing the risk of condensate buildup and water hammer. If the supply were smaller, steam would arrive to distant radiators too slowly, vents might trap air or condensate, and overall heating would be inefficient or noisy. For typical installations, this two-inch size is the standard minimum to ensure reliable operation and even heating.

In a one-pipe steam system, the supply line must be large enough to deliver enough steam to all radiators and keep condensate from blocking the line. A minimum of two inches provides sufficient cross-sectional area so steam can flow with a manageable velocity, reducing pressure drop along the main and minimizing the risk of condensate buildup and water hammer. If the supply were smaller, steam would arrive to distant radiators too slowly, vents might trap air or condensate, and overall heating would be inefficient or noisy. For typical installations, this two-inch size is the standard minimum to ensure reliable operation and even heating.