Butterfly Valves

Does the valve have vortex-breaking "fingers" on the downstream side of the disc?

The butterfly valve is Vanessa 3000 and actually I do not have if it has these 'fingers' on the disc or not.

We had a slightly similar problem with a large butterfly valve when it was near its closed end of travel (btwn 5%open to 15%open). To cut a long story short, we had to weld a butterfly valve bypass pipeline in, 25% of the origional line size and put a small butterfly control valve in that. Control strategy was: once the large valve reached closed, the little one in the bypass line was still fully open and that valve then started to throttle back to shut. The opposite in reverse, small one would open up and when fully open the big one would start to open. This prevented the big one having to make small changes near the fully closed position. Expensive, 2 valves, extra piping, a more complex control strategy ect. But fixed control problem.

Rok

Mr Rok

can you give me the control logic with diagram i will be obliged to u

Thank you very much for your valuable feedback.

We are waiting for some help soon from the manufacturer.

I will let you know if they come up with useful solutions to this problem.

Ayman

Seems like very good solution, posted by Mr. Rok.

As to U-sonic flowmeter, just wanted to add that I would investigate a chance to:

a) allow for longer averaging to eliminate erroneous output, which is a compromise though. Don't make averaging too long, say about 5-7 seconds may help.

b) replace U-sonic gauge for the one of more solid technology, like Vortex or Coriolis or Thermo Mass - selection will be driven by accuracy, flow rate, rangeability required, pipe size, straight run available and max pressure first of all.

Also, the idea of having a single meter to serve 2 applications - flow control and fiscal metering - is not always best and somewhat stingy when you build a metering skid. I'd look into that as well, as besides control problem - hidden fiscal losses may exist here and very likely they do.

Juri.

Why not use an adequate control valve like a globe Valve with Equal% plug

This could enhance ur control mechanism and fix ur problem