What is the maximum allowable size for blow-down valves on boilers exceeding 100 square feet of heating surface?

The maximum allowable size for blow-down valves on boilers with heating surfaces exceeding 100 square feet is established to ensure effective operation and safety of the boiler system. A blow-down valve is crucial for controlling the concentration of impurities in the boiler water, and the correct size is significant for efficient blow-down procedures.

Choosing a size of 2.5 inches for these valves is appropriate as it strikes a balance between ensuring sufficient flow for proper blow-down while also maintaining system integrity and safety. This size allows for rapid removal of accumulated impurities without causing undue stress or complications in the piping system.

In contrast, sizes that are too small, such as 1 inch or 2 inches, may restrict flow, leading to ineffective blow-down processes and potential issues in boiler operation. A size of 3 inches, while seemingly adequate, may be excessive for most applications, potentially leading to unnecessary costs or complications in the system design. Hence, 2.5 inches is the optimal choice for maximum efficiency and performance in blow-down operations in this context.