Stop Valves
(cut-off valves)
General
Stop Valves are the most common type of valve used in the home.
They are so named because their function is to stop the flow of water rather than regulate its flow. Their purpose is to cut off the flow to a designated fixture or run in the event of emergency so that repairs can be made. They may also be used to stop the flow to an outside faucet to prevent freezing. They usually have stems and seats and aren’t expected to be used frequently.
If the line they control needs to be drained when the flow is shut off, they may include an auxiliary opening on their side, just past the valve seat. This opening is controlled by a cap screw. When the valve is also closed, the cap may be opened to drain the water out of the line beyond that point. This type of valve is called a Stop and Waste or a Stop and Drain. Of course the valve must be mounted on the low end of the run for the pipe to drain properly.
Stop valves are often referred to as compression stops or sweat stops. This refers to the type of connection they require. A compression stop is connected to the water line by compression fittings. A sweat stop is soldered. An IPS stop has pipe threads.
An Angle Valve is mounted at a 90-degree angle (as seen at the left).
Supply Stop Valves
Supply Stops are valves used to cut off the flow of water to a fixture to allow for its repair or replacement.
One of these is installed at the supply line to each toilet, lav faucet, and sink faucet.
They are sold in a number of configurations from IPS to compression to sweat, but the most common is sweat. The outlet is usually ¼" CTS or 3/8" OD.
