Re: Flowmeter for hot Fluosilicic Acid

From: <Gordon.Reddek@Alcan.com>
Date: Mon Apr 26 2004 - 18:46:00 EDT

Steve,

I do not have experience with this one but I have had flow measurement problems in the past so I know the problems. Two comments: 1) You can not expect a cheap solution to this one so I would not discount the mass flow meters. Mass flow meters work on the coriolis force developed in a vibrating tube so there is no instrumentation in the flow. If your chemical does not attack vinyl ester or virgin teflon, why would a coriolis meter lined with one of those two materials not work? The liner will be stationary and therefore ignored by the meter. 2) Do you HAVE to install a meter? Can you measure flow indirectly be tracking the falling or rising level in a tank?

Cheers,

Gordon Reddek

"Steve McKenzie" <mechproj@xtra.co.nz> 26/04/2004 03:44 PM
Please respond to PipingDesign

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         Subject:        [PipingDesign] Flowmeter for hot Fluosilicic Acid

Hi there

I am having trouble finding a reliable flowmeter for HFA pH about 1, around 90 deg C, lots of solids. Its a killer brew - seems to attack anything hard and migrate through anything soft except vinyl ester and virgin teflon. Installation is at a Superphosphate manufacture plant.

Magflows have the Hastelloy C electrodes eaten away. Am dubious about ultrasonic - suspect inevitable solids deposits on the pipe wall will cause problems. Same for calometric. Mass flowmeters are a bit dear and the guts would rot out.

System is under pressure so I cant use a weir and level transmitter.

Was wondering about a bend meter with flushed DP tappings.

Any bright ideas out there?

Also pumps for same. Have tried Durco Hastelloy C (corrosion/erosion failure, Ash elastomer lined (migration of fluoride to shell). currently using Coro FRP - chemically OK but it will abrade/fatigue away

Cheers

Steve

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[Non-text portions of this message have been removed] Received on Mon Apr 26 18:46:00 2004