To add on to moltenmetal's comments, we had good results with Rosemount's (part of emerson) dP cells with welded tantalum diaphragms.. we were working with boiling phosphoric acid/hydriodic acid at 150-200 psi. While it's true that they won't see the froth, they still gave us a good indication...
We had similar issues with pumping molten iodine (MP=115C)..
Most of the pumps (including ceramic piston metering pumps with heat tracing, PTFE diaphragm pumps in a "hot box" thermostatically controlled to 130 C--I can give you references if you are interested) would end up either leaking at...
Disclaimer: I work in an R&D environment on small-scale equipment that doesn't need to last for decades, so this might not be the most relevant answer.
Could you replace the CS gooseneck material with something that is widely corrosion resistant (some kind of lined steel or maybe something like...
