OT: Chemical Flow Metering

[Phill77]

We have a wash facility which uses a venturi to draw an iron phosphate chemical from a tank into a high pressure water line running at 160 bar. The water flow rate is approx 17 litres/minute and the venturi is set to dose at a 3-7% dillution (0.85 l/min nominal).
If the strength varies outside this range we get a rusty product. The dosing rate is checked weekly by taking a sample of the dosed water and our chemists do some titration magic to establish the strength.
The venturis wear relatively quickly and we have to change them every 6 months.

We are installing a new wash system which will have 12 venturi instead of 2 so need to find a way to automatically alert production to an out of range dilution rate.

The only suitable method we can think of so far is to install a coriolis meter in the individual supplies to the venturi, but this is going to be expensive.

Does anyone have any better ideas?

 

[Tom Jenkins]

For the water lines a mag meter will be less expensive than a coriolis meter. They are often used on sewage, and many are available with replaceable liners to accommodate wear from abrasives etc. in the fluid.

For the chemical you may be able to use a positive displacement chemical feed pump (LMI or similar) and eliminate the flow meter on that line entirely.

 

[jtashaffer]

cidra flowmeters expensive but works great. It goes around your pipe instead of having to bolt it on.