End Connections

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E-mail jerry@freeflowinc.com Phone 800-933-4818 or 402-332-4818 Fax 402-332-3036< /font>

End Connections for Free Flow Inlet & Outlet Adapters
for Parshall Flumes

Inlet & outlet adapters allow installation of flume in a pipeline.
Adapters provide a convenient means of making the transition from round pipe to the square inlet of flumes.
Limited flow distribution can be achieved in the inlet adapter. Reasonable water velocity must be provided by the approach piping.
Short & long length adapters are available. Long inlet adapters provide more time for water distribution and calming.
The outlet adapters provide an area that is always wetted. This provides a convenient location for pH & temperature sensors, or sampler suction, without affecting flow measurements.

Inlet & outlet adapters are available with several different end connection styles:

- Grouting or caulking collars which allow the pipe ends to be inserted in the collar and grouted in place.
- Flat face fiberglass pipe flanges that match standard PVC and iron bolt circles & patterns.
- Pipe stubs with flexible neoprene couplings which allow quick installation. Watertight seal is made by using stainless steel band clamps furnished with the couplings.
- Internal expansion couplings that match the I.D. of the coupling.

Typical End Connections

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Caulking Collar Neoprene Couplings Flat Face Fiberglass Flanges

Inlet and outlet piping connections may be located on any wall or floor of the adapter in order to facilitate installation as long as the resulting arrangement promotes accurate flow measurement conditions.

Free Flow Inlet & Outlet Adapters
Dimensions in Inches

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Free Flow Parshall Flume Inlet and Outlet Adapter
Dimensions in inches

W	A	B	C	D	E	F	G	H	I	J	K	P
1	-	12	6-5/8	11-1/4	16	-	12	3-11/16	8	16	1-3/4	25
2	-	12	8-1/2	13	16	-	12	5-5/16	12-7/8	16	1-3/4	30-1/2
3	3	12	10-3/16	18	29	3	12	7	18	29	1-3/4	36
6	11	18	15-5/8	24	30	11	18	15-1/2	24	30	1-3/4	60
9	8	24	22-5/8	32	36	6	24	15	30	36	2-1/2	64
12	6	24	33-1/4	48-1/4	42	6	24	24	39	42	2-1/2	112-7/8
18	6	24	40-3/8	55-3/8	42	6	24	30	45	42	2-1/2	115-7/8
24	6	24	47-1/2	62-1/2	42	6	24	36	51	42	2-1/2	118-7/8

Long series inlet adapters, dim. "B" = 48 inches

SPECIFYING INLET AND OUTLET PIPE STUB ELEVATIONS
ON PARSHALL FLUMES

The pipe connections at each end of the flume & adapter assembly can be set at different elevations to suit the application. The elevations should be specified to promote accurate flow measurement and match field actual conditions. There are two possible situations when installing a flume with pipe end connections.

Situation One: The flume & adapters are to be installed in an existing pipeline.

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The in & out pipe stubs flanges are installed at different elevations such that the connections will line up with the existing pipe slope & result in the flume's crest remaining level.

The invert of the outlet pipe flange should be at an elevation that is even or lower than the floor of the flume at its outlet.

This insures that the flume will drain dry at a zero flow condition which is very important. With this as a reference elevation, & calculating the elevation of the inlet pipe's invert (due to upstream slope), it often results in the inlet pipe sitting slightly lower than the crest. If this is the case the crest will act as a dam in the line & cause a slight pooling of water in the upstream piping. Some pipelines are installed so flat (or have downstream obstructions) that there is always standing water in the line, even at zero flow. If this is the case, the flume should be installed at an elevation such that the crest of the flume is above the standing water level.

Situation Two: The flume is to be installed in a new line. The inlet & outlet pipe connections can be set with a substantial drop across the flume.

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In this case the inlet pipe stub should be set even with the crest (or inlet) of the flume. Upstream piping will drain dry at zero flow & there is no elevation difference between the inlet pipe stub & flume crest.

The outlet pipe stub should be set at least even with, or lower than, the floor of the flume at its outlet. For a Parshall flume, the downstream pipe's invert should be at least even with the lower end of dimension "K" on flume dimension tables.

If possible the pipe stub invert should be set lower than the flume's outlet to allow for head loss and make certain that the flume always operates in modular flow.

Most flume outlet adapters have a sump. The maximum amount of drop on the outlet pipe, using standard outlet adapters, occurs when the pipe invert is set even with the floor of the sump in the outlet adapter.

The pipe stub can be set even lower than the adapter floor if required, but the open area of the pipe will be reduced.

In installations where the upstream pipe is close to the flume inlet, a disturbance may occur at higher flows, where the depth in the flume is even with or higher than the top of the supply pipe. "Burping" and surges may result as the flow fluctuates above & below this level. Providing a longer approach section or locating the supply pipe at a higher elevation can eliminate this situation.

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