For proper flow measurement, a flume installation must be periodically inspected.  

This inspection should include the channel in which the flume is installed, the flow entering / exiting the flume, and the flume itself.

Channel inspection

• The upstream channel banks should be clear of vegetation or debris that could affect the flow profile entering the flume (upstream) or restrict flow out of the flume (downstream).

• Inspect the upstream channel to make sure that flow is not bypassing the flume.

• Inspect the downstream channel to make sure that scouring is not occurring.

• Any hydraulic jump should be at least 30 times the maximum head (H_max) upstream of the flume.

Flow inspection

• Flow entering the flume should be tranquil and well distributed.  

• Turbulence, poor velocity profile, or surging should not be present.

• The Froude (Fr) number should, ideally, be 0.5.

• As the Froude number increases so does surface turbulence.

• Flumes accelerate sub-critical flow (Fr < 1) to a supercritical state (Fr 1>) .  

• Flumes experiencing flows greater than unit (Fr = 1) will not accurately measure flow.

FLUME Direction

• For first time inspections, make sure the flume is installed facing the right way.

• The narrow, v-shaped end must be facing downstream.

Flume Inspection

• Flumes must be level from front-to-back and from side-to-side.  

• Earthen installations are particularly susceptible to settling due to wet / dry and freeze / thaw cycles.  

• Flow surfaces are to be kept clean of surface buildup or algal growth.  Scrubbing or a mild detergent can be used. 

GALVANIZED SPECIFIC​ MAINTENANCE

• Check for corrosion. 

• Any corrosion should be removed, the area dried, and then cold galvanization applied.