Selection of the isolation diaphragm for pressure transmitters?
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If pressure is to be measured in a medium containing 20% hydrochloric acid, hydrofluoric acid, or other fluorine-containing compounds, can a polytetrafluoroethylene membrane be used in a flanged pressure transmitter?
OP, my suggestion is to apply an F4 film over Hastelloy C, and then regularly check and replace the F4 film.
I recommend using a Monel-gold-plated diaphragm.
Recommending F4 without even mentioning the temperature – isn’t that a bit hasty? It is necessary to take into account factors such as temperature, pressure, corrosivity, and whether it is easy to solidify/crystallize, among others, for a comprehensive assessment
OP, the inspection cycle for F4 diaphragms is 1 to 2 months. Why? Because both hydrochloric acid and hydrofluoric acid are strongly oxidizing agents. Additionally, considering temperature and the wear caused by solid substances, the time can be shortened accordingly. I do not recommend gilded Monel; it is too expensive, and its practical performance is similar to that of Hastelloy C lined with an F4 membrane.
OP, the inspection cycle for F4 diaphragms is 1 to 2 months. Why? Because both hydrochloric acid and hydrofluoric acid are strongly oxidizing agents. Additionally, considering temperature and the wear caused by solid substances, the time can be shortened accordingly. I do not recommend gilded Monel; it is too expensive, and its practical performance is similar to that of Hastelloy C lined with an F4 membrane.
For applications with severe corrosion, Hastelloy C+F4 is recommended