End Adapters are specially shaped transitions that are molded or secured to the inlet and outlet ends of Parshall flumes to connect then to inline piping so that flow can be measured.  End adapters serve to transition flow from the round pipe to the rectangular cross-section of a Parshall flume in a controlled manner. 

The smoothness of the transition from pipe to channel is key to accurate flow measurement.  Transitions that are abrupt either in the lateral contraction of the flow stream or in rise into the flume can create poor velocity profiles and undue turbulence. 

Likewise, transitions that are too short and do not allow the flow to fully develop before it enters the flume will create accuracy problems that can be difficult to correct – particularly on mixed industrial or sanitary flows.

Inlet End Adapters

Openchannelflow’s Parshall flume end adapters are designed to provide a maximum of flow conditioning.  As flow enters the inlet end adapter it is abruptly expanded into the rectangular cross-section of the adapter. 

Flow then travels though a section of straight, rectangular channel so that a more normal velocity profile can develop.  The rectangular channel section of Openchannelflow’s end adapters are 50% longer than most other end adapters – providing more room to condition the flow and develop a more uniform velocity profile as the flow enters the flume.

After the rectangular channel section of the end adapter, the flow is smoothly directed into the entrance of the flume through the use of radius wing walls.  Radius wing walls have been shown to better transition flow into Parshall flumes than flat sided, vertical wing walls.

As the flow is moving through the inlet end adapter it is not only being shaped to the cross-section of the channel / flume, but also gradually rising up to the elevation of the flume’s floor.  The rise is at a 1:4 slope – more gradual that other manufacturers end adapters – as recommended by Dr. Parshall in his development of would become his namesake flume.

Outlet End Adapters

The outlet end adapter serves to ensure that flow exits the flume and does not back-up into the flume as it transitions into the discharge pipe stub. 

Depending upon the pipe stub size, one of two end adapters may be provided with the Parshall flume.