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How to select premium butterfly valves (3) Operation

  • Author:Ivory
  • Release on:2018-11-27

Manually operated butterfly valves require either a lever or a gear operator to open and close the valve. A lever handle can be used for smaller valves (up to 4 inches in diameter). An operator manually rotates the lever 90 degrees to pull the valve disc out of the valve seat to open the valve. Rotating the valve in the opposite direction 90 degrees will close it again. Typical rotation is counterclockwise to open, and clockwise to close. The only mechanical advantage here is the length of the lever acting on the fulcrum point turning the valve stem. The longer the handle, the easier it is to operate the handle, but too long a handle becomes impractical.

A gear operator is a mechanical operator where a hand wheel is attached to a shaft with a worm gear on one end that engages a central gear attached to the valve stem. This provides a mechanical advantage due to the ratio of the gearing. Gear operators require multiple 360-degree rotations of the hand wheel to achieve the 90 degrees required for open or close.