Measurement of Head Loss Across Trash Rack

[skm]

Can any one one help me with a tricky issue of head loss measurement in an intake water station well with multilevel intake opening with trachracks. This intake station has 4 intakes at different levels and are provided with trashrack to prevent debris from entering th intake well. Water is discharged from the bottom opening. We need to provide instrumentation to measure the degree of blockage of each screen/trashrack.

Thanking you in advance.

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[JEB66]

you could not use a differential perssure transmitter on both sides of the screen and subtract the difference?

 

[skm]

JEB66

Didn't get you. Do you meas use of differential transmitter across screen or other wise?

Any way let me explain. This intake tower is surrounded by water all around so the upstream head for all screen is same. Similary on the downstream of screen is the well which is again common for all inake points. Considering this, is it still possible to measure the head loss across individual screen.

I hope I am clear.

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[EdStainless]

How much level drop is there coming through the racks?
I supposed what you are trying to do is detecte a fouled rack.
If the level behind them is common, then DP won't work.

Have you stood there are looked at a fouled rack? Is the level right behind the rack any different from the others?

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[BJC]

Try installing a small pipe around the rack with an orifice in it. Measure the DP across the orifice. You don't care about the quanity of flow just the DP. These guys make DP insturments.

http://www.differentialpressure.com/

Google is full of others cheap to very spendy. You can get 4-20 Mill xmitters or switch alarms.
I would use 1" PVC pipe. Water will flow through it so you'll need some way to keep it clean. YOu may want to periodically back flush it from the screen wash system.

 

[bimr]

You can do this measurement either with a ultransonic or radar measurement similiar to what is done for flowmeters. Check with Endress + Hauser:

https://webas1.endress.com/sap/bc/c...FA280BC4394099F404179E4CC&compId=TI397FEN.pdf