However, I don’t know that either of your applications warrant a potassium formate based solution. I was adding it for others looking at this thread for chiller fluid suggestions.
It is appropriate for -30C. but that can easily be hit with a Propylene Glycol mix (Dynalene PG), and it’s not clear you need to run your chillers anywhere near that cold.
in a closed system, a Potassium Formate (HC50/PF50) will do ~200C, but in the open circulators you’ve got, it’s only good till 110C which isn’t hot enough for your purposes.
Dynalene’s Silicone based fluid is ~$1k for 5gal, I don’t know how that compares to the other silicone based fluids discussed above. I believe a silicone based fluid is your best bet for your WFE. Remember not to use silicone hoses if you go with a silicone based fluid.