fill fluid selection

[petrona]

I must buy the right fill fluid for two similar DPcells;

these fluids have contact with process fluid:
the first with sulfuric acid aqueous solution pH 2
and the second with soda aqueous solution pH 13.

I think that fluids must have some Characteristics:
density > process solution
immiscible with process solution
no reactivity with process solution
operative temperature 0-40°C
low volatility

What do you propose?
Thanks

 

[moltenmetal]

Fluorocarbon liquid. 3M product. Not cheap, but will definitely work.

Or diaphragm seals...

 

[Compositepro]

Are you talking about a U-tube manometer? I can't think of anything else that would not use diaphragms.