Controlling High Velocity Flows with Energy Absorbing Manholes

For a flume to operate correctly, the approaching flows must be subcritical and well developed. Sometimes, however, the approaching flow has high velocity or is turbulent due to steep pipe slopes or pumped flow. To control and condition these flows, Openchannelflow offers Energy Absorbing Manholes.

fiberglass energy absorbing manhole controlling high velocity flows

Utilizing the same no maintenance, high strength fiberglass manholes that we use for our Packaged Metering, Screenings, Grinder, and Diversion Manholes, Openchannelflow Energy Absorbing Manholes integrate energy dissipating baffles to slow the velocity and dissipate energy. These baffles are sized to be slightly larger than the incoming pipe.

Energy Absorbing Manholes are available for line sizes from 4 to 48 inches in diameter and for all locations (traffic, pedestrian, non-traffic).

How Energy Absorbing Manholes Work

High velocity flow enters the Energy Absorbing Manhole and hits the dissipating baffle
The flow is slowed and energy absorbed
Passing on either side of the baffle, the slowed flow is then smoothly transitioned out of the manhole by curved wing walls mounted on either side of the outlet pipe

Where Energy Absorbing Manholes Are Used

When used to aid flow measurement, Energy Absorbing Manholes are typically placed several feet immediately upstream of a Packaged Metering Manhole.

The combination of Energy Absorbing and Packaged Metering manholes allow users to accurately measure flows on high velocity lines with the Energy Absorbing Manhole ensuring the velocity of the flow entering the flume is sub-critical and well developed.

aluminum top energy absorbing and packaged flow metering manholes

By being able to place an Energy Absorbing Manhole directly upstream of a flow metering manhole, only one site needs to excavated and one pad poured, considerably reducing installation time and cost.

Energy Absorbing Manholes can also be used as part of a drop manhole configuration with flow hitting the dissipation baffle and then dropping down into the lower portion of the manhole.