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Valve Basics


Valves Safety Tips

 

  • Plastic valves should not be used in steam, gas or compressed air lines. However, valves can be used with hot and cold fluid systems.
  • Never over-tighten any valve, as you can strip the threads and ruin the valve.
  • Whenever turning on a main water supply valve that has been turned off, always be sure to turn the water on slowly to avoid water banging in the pipes.
  • When soldering copper pipe to a brass valve, always open the valve completely to avoid excessive heat damage.
  •  


    Gate Valve

     

  • Uses a sliding wedge to move across the waterway, in either a rising or non-rising action.
  • Used to completely shut off or open a waterway. Does not control the volume of flow.
  • In some models, either opening of a gate valve may face the pressure side of the line, while in others, an arrow indicates the direction of water flow.
  • Because they allow the complete passage of water, use on supply lines that are in constant use.
  • A Connector Gate Valve uses a union fitting on one side
  •  


    Boiler Drain Valve

     

  • A horizontal faucet with male hose threads on the outlet side and either male or female IPS threads on the inlet side.
  • Originally designed to drain water from a boiler, hence the name.
  • Today, they're usually used for laundry machine hookups.
  • Newer models of laundry valves have a single lever that controls the hot and cold water supply.
  •  



    Ball Valve

     

  • Uses a large lever to turn a ball that closes or opens the flow of water with one quick quarter turn.
  • Are the standard for natural and LP gas, replacing the older plug valves that were traditionally used as gas valves.
  • Available in either metal or plastic, threaded or non-threaded types.
  • Ball valves with double-stem seals provide greater durability.
  •  


    Globe Valve

     

  • Used when a valve must be opened and closed frequently under high water pressure.
  • Used to control volume of flow. These valves have two chambers with a partition between them for passage of water that must change course several times from port to port.
  • Should not be used in water supply lines for occasional shut-off purposes.
  • An angle valve is similar to a globe valve, but has its ports at right angles. Install at a turn in piping to eliminate the necessity of an elbow (this is often preferred to using a globe valve and elbow).
  • An angle valve has greater water passage than a globe valve. Since there is only one change in direction of flow, there is less resistance.
  • A Connector Globe Valve uses a union fitting on one side
  •  


    Pressure Relief Valve

     

  • Used to protect water heaters or hot water storage tanks.
  • When the water pressure reaches a dangerous level, the valve opens and discharges water. Cold water then flows into the tank and stabilizes the water pressure
  •  



    Stop & Waste Valve

     

  • Has a small opening on the non-pressure side to allow drainage when it is in cut-off position. Helps prevent freezing of water lines in winter.
  • Also known as a bleeder valve or drainable valve.
  • Comes in threaded, sweat, flare and slip joint ends. The latter two are municipal and emergency valves.
  • Flat head or socket head are common residential types have a socket head that takes a 3/8" key rod.
  •  


    Check Valve

     

  • Operates automatically, permitting flow in one direction only.
  • Sometimes combined with a throttling or shut-off valve. Some communities require a check valve in cold water lines between the water heater and meter.
  • Used to prevent water pumped to an overhead tank from flowing back when the pump stops.
  • Some check valves are designed for use with vertical pipes only. Therefore, it will not work if installed upside down. The closing device is a disk, ball or clapper that falls shut by gravity when installed vertically.
  • Another variety is the Swing-Type check valve, which is a small, smooth swing-type gate located in the center of the valve. As water is pumped through the flow side of the valve, a gate swings open to allow water to pass. If water attempts to back up through the valve, the gate is forced shut against the pressure side of the valve.
  •  


    Shutoff Valve

     

  • Used to shut off or turn on the water to a water supply tube.
  • Generally used underneath sinks and toilets.
  • Also known as a speedy, angle stop, water supply valve, cutoff valve, lavatory straight valve or stop.
  • Made of metal or plastic in either a straight or 90 degree configuration.
  • Fairly easy to install.
  •  

    Courtesy of NRHA.org








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    If you have a question you would like answered, please visit our Community Forums.
    posted Dec 11, 2008

    Trying to look at plumbing, shut-off valves, valve basics.
    There are NO pictures, they are blanked out. Whats going on?


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