American Society of Mechanical Engineers (ASME) Practice Exam

The minimum size of the feed connection to a boiler with a heating surface of 100 ft² or less is 1/2 inch. This size is specified because it ensures adequate flow of water into the boiler for proper operation and efficiency. The design parameters of boilers take into account the heating surface area and the corresponding feedwater requirements to maintain safe and effective performance. A 1/2 inch feed connection can adequately handle the necessary water flow for smaller boilers, ensuring that the system operates effectively without the risk of issues such as water starvation, which can lead to overheating and damage. The standards set for boiler components typically ensure that all connections are sized appropriately based on the heating surface area, with established minimums to maintain safety and performance standards. Larger connections, such as 3/4 inch or 1 inch, while they may offer a higher flow rate, are unnecessary for a boiler of this size, and using them could lead to inefficient operation or increased costs. A connection size of 1/4 inch would be too small and inadequate to meet the required flow, potentially leading to operational issues.