PVC ball valves allow you to turn the flow of liquids on and off quickly, while creating a watertight seal. These particular valves work well for pools, laboratories, food and beverage industries, water treatment, life science applications and chemical applications. These valves have a ball inside that rotates on a 90-degree axis. A hole through the center of the ball allows water to flow freely when the valve is on the "on" position, while stopping flow completely when the valve is in the "off" position.