Brown Fluoride residue in Flowmeter - what is it?

[InstrumentDept]

I'm having an issue in my Hydrofluorosilicic acid (Fluoride) metering equipment where there is a brown substance that builds up and blocks the orifice. I cant find anything on the strainers ahead of it, nothing in the pumps or on the piping, just in the flowmeter. The meters wetted parts are fluoride compatible. Anyone have an idea what this material can be or what is precipitating it out of solution?

 

[bimr]

If you are using raw water as a carrier fluid, the hardness in the water is likely to be precipitating, You can use a water softener to remove the hardness (calcium).

 

[InstrumentDept]

At this point in the stream its just the chemical, chase water comes after this metering is done. We tried having it analyzed and the lab nearby said it needed to be water soluble and it wasn't.

 

[EdStainless]

If you really care have a sample tested by X-ray diffraction.
That will tell you what the compound actually is.
You could use XRF just to get a general chemical picture.
Of course this deposit will take a hot acid mixture to digest.
Though some of these compounds are virtually impossible to dissolve.

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P.E. Metallurgy, consulting work welcomed

 

[InstrumentDept]

It would be a tiny sample, the orifice of the meter is 3/32 inch and that is the only place we see it develop. I guess I can start collecting it until I get a good sized sample.

 

[bimr]

There are a number of processes used to prepare Fluorosilicic acid It may be that there is an excess of silicate in the solution that precipitates. Ask your chemical supplier.