North Carolina Surface Water Practice Exam

The primary function of a check valve is to prevent backflow. Check valves are designed to allow fluid to flow in one direction only, effectively stopping any reverse flow that could cause contamination or damage to systems. They operate automatically, typically using a hinged disc or ball that moves away from the seat as fluid flows in the intended direction and closes when the flow reverses. By doing so, check valves play a critical role in maintaining the integrity of piping systems, protecting equipment, and preventing water hammer and other issues associated with backflow.

Other options, while related to fluid dynamics, do not represent the primary function of a check valve. Allowing water to flow in both directions contradicts the fundamental operation of a check valve. Measuring flow rate is a function typically performed by flow meters, and regulating pressure is done through pressure relief valves or regulators, rather than check valves. Thus, the role of a check valve is specifically centered on the prevention of backflow, ensuring a system operates safely and efficiently.