Fusor Forums

Andrew, I'm curious about the details of the not-high-voltage portion of the fluorinert loop. It looks like you used a lot of swagelok - including teflon swagelok which I've never encountered before.

Obviously in many cases (especially if using PC liquid cooling equipment) there's going to be plastics - which of these are usable?


The other side of things is that I'm actually more worried about corrosion than shorting out HV. It looks like there are some... Interesting coolants in the PC world as well. (NOT the ones that are bright green and UV-fluorescent for aesthetics).

Please excuse one answer to a question addressed to somebody else.
Some of my co-workers worked on a Fluorinert-cooled instrument during years when I worked elsewhere, and I will ask about it on Monday. Meanwhile, LMGTFY. Found a lot here:
https://detector-cooling.web.cern.ch/de ... rinert.pdf
and
https://www.besttechnologyinc.com/preci ... -transfer/
including

I think it’s generally agreed that the fluorinert fluids are environmentally unfriendly, but they are used in such small amounts that it is also generally agreed that they are not a significant problem. I think their astronomical cost will insure that they are never used in sufficient quantity to constitute a significant environmental risk.

Teflon and nylon tube are both good, as are viton o-rings. You can get teflon and nylon ferules and fittings from swagelok.

We can not import Fluorinert into New Zealand as it is a super green house gas nasty
NZ is about to ban SF6 as well alot of switchgear to swap out

From the interweb
"Global Warming Potential
Fluorinert perfluorotributylamine absorbs infra-red (IR) wavelengths readily and has a long atmospheric lifetime. As such, it has a very high global warming potential ("GWP") of 9,000, and it should be used in closed systems only and carefully managed to minimize emissions." ie no vents to atmosphere at all

therefore no amateur sytems should use this!!!!!

I will mention that propane is an excellent heat absober (better than water) and works great as a coolant; while not as hazardous as hydrogen, it is explosive in air (in the right mixture ratio's) so it must be used with extreme care and no leaks can occur. I have built a number of refrigerator systems using this substance. More importantly, it is an excellent electrical insulator. If one is comfortable using this very flammable gas it is easy to liquify and use as a coolant just know its extreme dangers.

Last year I used unpressurized liquid propane as a freezing bath, outdoors in a well ventilated area, with excellent success.
Started with a thermos full, drawn from a BBQ tank so old it still has a POL valve. Glad to be with Dennis on a safety thing!

Am reminded of one classic HV high bandwidth scope probe: the Tektronix p6015.
They came with freon insulation (dichlorotetrafluroethane), as vapor with some visible liquid so you could tell when it needed to be refilled.
https://www.eevblog.com/forum/testgear/ ... ke-or-buy/
Amateurs have used butane as a replacement dielectric, with similar pressures & HV breakdown voltage.
https://yarchive.net/car/high_voltage_probe.html

Aside from ozone and GWP issues, simple hydrocarbons are less toxic than CFC's and HCFC's and fluorocarbons.
Many people think of freons as nontoxic (with asphyxiation risks), but then why do teens huff Dust-Off when they want to get a buzz?
Look at the Threshold Limit Values in occupational safety tables; tolerable concentrations in air are higher for propane and butane.
Same applies to the IDLH (Immediately Dangerous to Life or Health) concentrations, when not bounded by Lower Explosive Limit.
[edit] Looks like NIOSH has revised them down to generally 10% of LEL, when the poisonous aspect doesn't get you first. https://www.cdc.gov/niosh/idlh/default.html