Fluid at 5000psi and 700 F

[batthina]

I am trying to find a liquid that can be pressurized to 5000psi and heated up to 700 degF.
I will be using this fluid in a pressure vessel with heater bands around it. What I am trying to do here is very similar to HIPing, where I want to substitute gas with a liquid. I will be HIPing Polymers/plastics. I am not sure how water behaves at these conditions. Also, I was looking into some polymer quenchants that I thought I could use. But, could not get much info.

Looking forward to hear your suggestions.

Thank you.

 

[sshep]

Assuming you want to get a heat transfer fluid from a reputable producer, can you use:

Syltherm 800 (Dow) or
Therminol 75 (Solutia formerly Monsanto)

both are good up to and above 700F.

best wishes,
sshep

p.s. what is HIPing?

 

[Compositepro]

Silicones are a good choice. There was a product once (which I don't think is available anymore) that was crumbs of very soft silicone rubber. It would compress into a solid mass and as it was heated it would expand and generate pressure in a sealed chamber. The advantage of solid crumbs is that you don't have to deal with the mess of liquids.

 

[MikeHalloran]

I'm real curious about what plastics will survive at 700F.



Mike Halloran
Pembroke Pines, FL, USA

 

[batthina]

Thank you all for your responses.
Mike - The normal sintering tremperature for PTFE is around 700F.
I am trying to apply pressure isostatically on the polymer sample. It could be a 2" OD, 7" long solid billet inside the pressure vessel. I am not sure if we can achieve equal pressures in all directions using silicones. Please advice.

 

[batthina]

sshep - HIPing is 'Hot Isostatic Pressing', a process generally used to eliminate voids and improve densification in metals.

 

[Compositepro]

You must use a material that will apply pressure without penetrating the pores of your part, or use a barrier material. I think the silicone rubber crumbs are just what you are looking for. I believe they were made by Dow. Check with them or G.E. silicones. They may not be marketing this to the thermoplastic composites industry anymore but it may still be available. Check out:

http://www.freepatentsonline.com/4889668.pdf

Won't conventional HIP equipment work for you?

 

[batthina]

None of the conventional HIPing specialists were ready to perform this in their units as they were afraid of contamination. We thought about the pressure vessel idea and wanted to use liquid instead of gas (argon is mostly used in conventional HIPing).

 

[davefitz]

water at 5000 psia and 700 F may behave as a supercritical solvent , if there is a slight temp excursion above about 720F. Some strange phenomena occur with supercritical fluids, so be prepared to be surprised.

when operting at high pressure , be sure that there is positive relief of overpressure. Sometimes, if there is a temp excursion , there may be new chem species formed that may lead to rapid overpressure unless such relief is provided.

 

[MikeHalloran]

How about just filling a 'tin' can with PTFE, and HIPping that?



Mike Halloran
Pembroke Pines, FL, USA

 

[batthina]

One more problem we had in going for conventional HIPing is the size of our samples. Normal HIPing accomodates something around 4000 samples of the size that we were going to try. I could find one firm that had a small scale unit, but they they gave us quote of >$14000 for just 3 samples. This was going to be with the some encapsulation (probably Al) around the PTFE sample.