Butterfly Valves Guide

Butterfly Valves are a kind of valve that regulate or control fluid flow via a rotating disc. They feature quarter-turn capability for full open or full close, simple lever handle or actuated operation and have a relatively large coefficient of volume (meaning low pressure loss at high flowrates). Butterfly valves are especially popular due to their light weights, compact size and comparatively low costs.

by Tom Hansen P.E.by Tom Hansen, P.E. | ©Dultmeier Sales

Wafer Body Butterfly Valves

Wafer butterfly valves (or wafer body butterfly valves) are more economical than their counterpart, lug butterfly valves. Typically manufactured with EPDM & Buna seats, stainless discs and stainless stems, wafer butterfly valves are compact and versatile. The lever handles can normally be used to set the valves in ten different positions ranging from closed to fully open. They can also be controlled with a variety of air and electric actuators. They are designed to prevent backflow in systems made for unidirectional flow. A flat valve face upstream and downstream of the valve, as well as a tight fitting gasket or o-ring helps this process.

Dultmeier Sales stocks wafer body butterfly valves designed to fit between standard 125 lb. / 150 lb. ANSI flanges with "thru" bolts that run along the outside rim of both flanges.

Lug Body Butterfly Valves

Lug butterfly valves, while slightly less economical than wafer valves, offer many of the same features. Installed between two flanges with a separate set of bolts for both, lug valves allow piping to be disconnected on either side of the valve without disturbing the other side.

Dultmeier Sales does stock lug body butterfly valves which also have the advantage of being used in "end of line" (dead end) applications with a flange on just one side of the valve, but typically feature a reduced pressure rating when used as such.

Dultmeier Sales stocks Wafer, Lug Style and Actuated Butterfly Valves from Keystone & Pratt.

Stock butterfly valve bodies are standard in cast iron (since bodies are a non-wetted component) with EPDM seats and stainless discs & stems. EPDM seated butterfly valves are compatible with water, fertilizer and some diluted chemicals but should not be used with fuels, oils or other hydrocarbons. Buna seated butterfly valves are compatible with standard diesel fuel, many oils, water & most fertilizers. Viton® seats & teflon coated EPDM or Teflon coated Buna seats are also available.

Always confirm seat material, disc & stem compatibility with all products you will be running through the butterfly valves.

Tom Hansen, P.E.  |  Dultmeier Sales
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