Challenges in HF Flow Metering in the Industry

Flow measurement of Hydrofluoric acid is quite challenging being one of most aggressive acids to deal with. It is used in glass etching, automotive and industrial wheel cleaning, brick cleaning, semiconductor manufacturing, metal purification, and other industries.

Due to its highly corrosive nature Nickel and Monel metals are generally used for handling this acid. From elastomer perspective polyethylene, polypropylene and polyvinyl chloride (PVC) are normally used elastomers however at times special polyester resins reinforced by glass or graphite fibres are used when handling the acid at elevated temperatures.

One of the client producing Polytetrafluoroethylene, PTFE commonly called Teflon using four ingredients — fluorspar, hydrofluoric acid, chloroform, and water, combined in a chemical reaction chamber heated to between 590-900°C.

Client was using an in-line Electromagnetic flow metres for measuring Hydrofluoric acid. There were frequent failures owing to acid harsh and corrosive nature. This led to operation disruption thereby affecting plant production apart from increasing maintenance cost.

Client then opted non-contact type clamp on flow meter to overcome the above stated issues and got following benefit :-

  • Non-Intrusive clamp on flow meters were installed in running plant and no shutdown was required since the transducer were strapped on pipe .

  • Frequent maintenance as used to be before from using in line flow meters virtually became maintenance free using clamp on meters.

  • Clamp on meters were able to provide both volumetric and mass flow measurement

  • Additionally clamp on meters also gave measure of acid concentration since it has direct bearing on sonic velocity which is measured to calculate flow.

With above advantages client had substantial benefits both in terms of money savings as well as better operability .

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