C-36 Plumbing Contractor Practice Exam 2026 – Comprehensive Test Prep

To determine the appropriate size of the fixture supply pipe for kitchen and service sinks rated at 4 hwsfu (hot water supply fixture units) each, it's essential to consider the total demand imposed by these fixtures. In this case, with each sink rated at 4 hwsfu, the total loading for two sinks would be 8 hwsfu (4 hwsfu x 2).

Plumbing codes generally provide guidance on the sizes of supply pipes based on fixture units. For a total demand of 8 hwsfu, a 1/2" supply pipe is adequate to provide the necessary flow without risking pressure loss. This size is commonly used in residential applications for providing water to single fixtures or small groups of fixtures, ensuring that they have sufficient flow rates for typical domestic use.

In contrast, larger pipe sizes would generally be used for higher fixture unit ratings or when serving multiple fixtures that demand a higher flow rate simultaneously. Therefore, selecting a 1/2" supply pipe strikes a balance between providing adequate water supply for both kitchen and service sinks without being excessively large for the anticipated demand.