Backflow Prevention Practice Exam

Check valves are designed to prevent backflow primarily by utilizing the principle of pressure differential. This principle relies on the difference in pressure between two sides of the valve to determine its position. When fluid is flowing in the intended direction, the pressure on one side of the valve is greater than the pressure on the opposite side, keeping the valve in an open position. If there is any reverse flow or back pressure, the pressure on the upstream side decreases, allowing the valve to close due to the higher pressure on the downstream side. This action effectively blocks any backward flow, thus preventing contamination of the clean water supply.

While gravity can influence the movement of some types of valves, particularly in non-pressurized systems, check valves predominantly operate based on the pressure differential principle. Water level control and mechanical advantages may play a role in specific applications, but they are not the fundamental mechanism by which check valves function. The reliance on pressure differences is what makes check valves a reliable choice for maintaining the integrity of water systems and preventing backflow.