A butterfly valve provides a convenient way to regulate and control flow between sections of pipe or tubing. Its lightweight construction of stainless steel, aluminum, steel and PVC makes it serviceable in residential settings as well as in commercial applications. The butterfly valve was originally intended for use with water, but it is now widely used for a variety of applications. Current uses for a butterfly valve include applications that involve gas, steam or air in addition to liquids. In some cases, dry materials are also handled by a butterfly valve.

   


Operating principle
The basic principle of operation of a butterfly valve is the opening and closing of a metal disc, resembling the way the wings of a butterfly move. When the disc is in a position that is parallel to the flow, it presents no blockage. However, when it is perpendicular within the conduit, an effective block is created. A butterfly valve is actuated manually by a handle or a wrench usually, unless a gear is installed for the purpose. Activation is also accomplished by an outside power source such as that provided by electric, pneumatic or hydraulic operators.

Dead man’s handle
A spring return butterfly valve is one that has certain requirements that increase the safety of operation. A handle that is sometimes called a “dead man’s handle” requires the operator to make sure that the valve is left in the proper position, either open or closed. This feature requires the operator to maintain the existing pressure within the conduit.

Prep for installation by cleaning all parts
• Make sure that all surfaces of the pipe or tubing are clean.
• Clean any gaskets or flanges that are used in the installation
• Locate the disc that is attached to a rod in the valve, and wipe it off.
• Turn the disc to a closed position.

Install the flanges
• Hold the flanges of the valve snugly against the wall of the pipe or tubing.
• Make sure to form a tight seal that can prevent any leaks.
• Tighten the flanges slowly.
• Assure that there is adequate tension when the flanges are mounted on the pipe or tubing, as this is what allows the valve to open and close in operation.

Install the valve
• Slowly slide the butterfly valve into position, between the rims of the section of pipe or tube.
• Avoid damaging the gasket, as it is the seal for both the flanges and the valve.
• Locate the bolt holes.
• Match a bolt to the proper corresponding hole.
• Tighten the bolts in opposition, choosing one that is located on the opposite side.
• Do not tighten the bolts by working on them in a circle.

Check it out
• Use the lever on the outside of the valve to open it.
• Watch to see that the valve has enough space to turn within the pipe or tube.

Review safe practices
• Read the safety precautions again.
• Stay within the recommended ratings for pressure and temperature tolerances.
• Use the spring return butterfly valve only for applications that are recommended by the manufacturer.