RE: Flowmeter for hot Fluosilicic Acid

From: <Steve>
Date: Mon Apr 26 2004 - 19:27:00 EDT

Hi Gordon

1. I have several issues with Coriolis meters. The first is that the vibrating tube is normally metallic. Coating the tube with say vinyl ester will affect its response. There is some possibility of deposits forming and upsetting the vibration/accuracy. The few instances where I have heard of coriolis meters being used in slurry, they wore out real quick. Second they are too dear to try without some form of guarantee. ABB, Foxboro and Krone have all indicated poor service life could be expected.
2. The flow under consideration is a recirculating one, unfortunately, so level measurement is not practical. Cannot arrange a weir as all eternal flow is inside pipes. Looked at using a peristaltic pump for combined pumping /flow measurement but there are no suitable tube liner materials.

We will crack it though.

Cheers

Steve
-----Original Message-----
From: Gordon.Reddek@Alcan.com [mailto:Gordon.Reddek@Alcan.com] Sent: Tuesday, April 27, 2004 10:46 AM
To: PipingDesign@yahoogroups.com
Subject: Re: [PipingDesign] Flowmeter for hot Fluosilicic Acid

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

         To:     PipingDesign@yahoogroups.com
         cc:
         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

---

PipingOffice - Excel Spreadsheets for Piping Calculations http://www.pipingoffice.us/

---

Main site: http://www.pipingdesign.com

Yahoo! Groups Links

[Non-text portions of this message have been removed]

---

PipingOffice - Excel Spreadsheets for Piping Calculations http://www.pipingoffice.us/

---

Main site: http://www.pipingdesign.com

Yahoo! Groups Links Received on Mon Apr 26 19:27:00 2004