Basic Wastewater Operator Practice Exam

What is a valve called that allows water to flow in one direction only?

1. Plug valve

2. Butterfly valve

3. Check valve

4. Gate valve

The correct answer is: Check valve

A valve that allows water to flow in one direction only is known as a check valve. This type of valve operates automatically and is designed to prevent backflow, ensuring that the fluid only travels in a specified direction. Check valves are commonly used in various applications, including wastewater treatment, to protect systems from reverse flow that could cause contamination or damage. In contrast, a plug valve is typically used to start or stop flow and does not inherently prevent backflow as its primary function. Butterfly valves are often used for regulating flow but can also allow reverse flow if not otherwise managed. Gate valves serve primarily the purpose of fully opening or closing a pipeline but do not prevent backflow either. Thus, the defining characteristic of a check valve is its ability to permit flow in one direction while blocking any reverse flow, which is essential for maintaining the integrity of many water systems.