Oilers/Plant Tenders (HHC) Civil Service Exam 2025 – 400 Free Practice Questions to Pass the Exam

A valve that allows oil to flow in one direction only is generally referred to as a check valve. This type of valve is specifically designed to prevent backflow in a system, ensuring that the fluid moves in a designated direction. The mechanism of a check valve typically involves a disc or flap that opens to allow flow and closes when the flow reverses, effectively blocking any backflow. This is crucial in applications such as oil transport systems, where backflow could lead to system inefficiencies or damage.

The other types of valves mentioned in the options serve different functions. A control valve is used to regulate the flow of fluid by varying the size of the flow passage, while a regulating valve maintains the pressure and flow within desired limits. A ball valve, on the other hand, has a spherical disc that controls flow and can be fully opened or closed, but does not specifically limit flow direction like a check valve does. Therefore, the distinct function of the check valve in preventing backflow makes it the appropriate choice for this question.