Submersible canister mixed flow pumps and air release

[JohnWeal]

We have 9 pumps fixed speed delivering 1.05 m3/s. Each pump is installed in a 1100mm steel canister. The depth is approximately 8m.
At the top, we have an air release and vent to prevent. Vacuum when the pump stops and also to release the same air when the pump starts. The air release limits the velocity in the canister to around 0.6 m/s.

As we have an upstream screen in the channel, this is a 12mm bar screen. This will not stop sediment arriving at the pump as we have a river intake.
Now the sediment modelling is very difficult to predict so we expect some sediment to arrive at the pump and then transferred to the water treatment facility.

So my question, has anyone had experience of the air vent valves for this type of application and if so, any blockages caused by sediment or other small debris in the pumped flow?

 

[QualityTime]

Even if you did not have the air release and vent valve or it plugged up, what process downstream will be affected by the air burp. Will your piping collapse under the negative pressure conditions? Will you get air locks in your piping? Is it really required at this point in the process train?

 

[Artisi]

If the liquor contains sediment/ rubbish it will one day block- as QT has said what will be the effect.
What is the discharge head on the pumps - if low you can maybe fit an open ended riser to handle the start / stop conditions

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)