Below is a list of Triple Offset Butterfly Valve manufacturers from Allentown, Pennsylvania. Triple offset butterfly valves are mechanisms that control the flow of fluids in pipes while being eccentric in three places. Butterfly valves consist of a seal around the wall of a pipe, a round or elliptical disc and a control lever. These valves are quarter turn valves meaning that the control lever must only be rotated 90° in order to close off the pipe.