There are several different types of check Stainless Steel Ball Valve. A ball check valve consists of a ball that sits over the valve's opening. When liquid flows past the ball, it pushes the ball away from the mouth of the valve, which gives it room to flow through the pipe. When the liquid begins to flow the other way, however, the ball fits tightly over the valve opening, essentially plugging it.
Most valves work in a similar way, although they may not contain balls. For example, swing check valves contain a swinging door on hinges that blocks backward-moving material, and split disk check valves contain a folded metal disk that springs open when the material moves backwards.
1 Shut off the water supply to the check valve. Follow the water line backwards (the flow of water is indicated by an arrow on the check valve) and switch off the next valve. Wait 15 to 20 minutes for the water pressure to subside.
2 Check the valve for debris by tapping its side with the handle of a screwdriver. A rattling sound means the Double Check Valve is fine, but inconsistent grinding or squeaking indicates that the valve is stuck on some form of debris. If the check valve is of the 90 degree (right angle) variety, remove the top of the valve (use the channel locks to turn the top of the valve to the left) and check the inside of the valve directly. There should be a dropping ball-pin on the inside, but nothing else. Replace the top of the valve.
3 Stand near the valve and have an assistant turn the water supply on for five seconds before quickly shutting it off again. Put your hand on the valve and place your ear near to it. If you feel or hear any water running, it is a sign that the valve's seal is leaking. Most of the time, however, you will hear and feel a gentle "click" sound as the valve closes and water will cease running through the valve as the water is shut off.
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