Hydraulic model testing Air pockets in pipelines

If a pipeline has pronounced high points, undissolved gases can become trapped there which increase the flow resistance of the pipeline as a whole. This results in energy losses and reduced flow rates. In this hydraulic model test, KSB examines and demonstrates the effects of air pockets in pipelines and the various options for eliminating air at various flow velocities.
The model setup consists of a pipeline with pronounced high and low points.
It is supplied with water from a pump installed in a water tank. At the end of the pipeline the water is discharged back in the same tank.
The flow rate and therefore the flow velocity are controlled by a gate valve on the inlet side and discharge side of the tank.
The head is indicated by the water column in the riser pipe. The flow rate is indicated on a display.
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[@mikemoren532]

Do you happen to have or know of a table for various pipe diameters showing what pipeline velocity is required to discharge air pockets for different degrees of vertical changes in pipe (i.e. 30-deg., 60-deg., 90-deg [vertical downward])? This would be very helpful.

[@Steve_Mazza]

Theoretical and experimental results vary. I found a cool paper attempting to survey the best available publications on it, and integrate that data into a comparative graph (numbered page 47). eprints.hrwallingford.com/551/1/SR649.pdf You will have to calculate the x-axis term based on pipe backslope (in radians). And calculate the y-axis term based on flow velocity, pipe diameter, and gravity. (Watch the units of each term.) There's quite a variation in predictions ... but it can give you a general idea if your scenario is good or bad.

[@naw3967]

good information.nicely explained!