Insulating Oil : What oil should I use? / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

Insulating Oil : What oil should I use?

1 2 3 next

Move Thread

LAN_403

Kiwihvguy

Wed Dec 29 2010, 02:14AM

Registered Member #3395 Joined: Thu Nov 04 2010, 08:42AM
Location: Christchurch, New Zealand
Posts: 193

Anyone know what's the best oil to use for insulating stuff apart from mineral oil?
I will be needing it for my Quad MOT Stack sometime.

Patrick

Wed Dec 29 2010, 02:30AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

I have authored two threads on the HV forum, that deals with this, use the search function.

Any food oil will work for MOTS--corn, vegetable, olive, soy, peanut, and one more I cant remember. Anyway, olive is most expensive, corn and vegetable are cheap in large quantities. (Here in US, CA.) In your case I would use corn or vegetable oil... but you could use non-detergent 40W motor oil, mineral oil, or hydraulic fluid.

However, I will warn you all of these oils, by there nature, are non-polar fluids. So they will leech out the plasticizer in soft tubes and soft wires. Loss of the plasticizer will lead to soft plastics turning rock hard. Hard plastics will be uneffected. (This may not pertain to your app.)

Killa-X

Wed Dec 29 2010, 05:38AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

About that last part patrick...The MOTS themselves, are fine in this solution, right? I was told its best to have the terminals above the oil because the oil can leach through the wires and possibly release on the surface.

Would storing the mots and oil in a 5-gallon plastic bucket be ok? I plan mineral oil...

Had to ask because I too, am doing a quad stack. I plan mineral oil, but is nice to see others ideas.

Patrick

Wed Dec 29 2010, 06:45AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Killa-X wrote ...

About that last part patrick...The MOTS themselves, are fine in this solution, right? I was told its best to have the terminals above the oil because the oil can leach through the wires and possibly release on the surface.

I cant think of a reason why oil would damage a MOT. But I dont know what you mean about the terminals? Although leaks through stranded wire are possible.

Killa-X wrote ...

Would storing the mots and oil in a 5-gallon plastic bucket be ok? I plan mineral oil...

Yeah, a ready made container meant to be liquid tight, would save you from build time/cost, and ensure little chance of leaking.

Patric

Wed Dec 29 2010, 04:29PM

Registered Member #2899 Joined: Wed Jun 02 2010, 06:31PM
Location: Deinze, Belgium
Posts: 255

I have very good experience with paraffin, it melts at 52Â°C.

Xray

Thu Dec 30 2010, 01:03AM

Registered Member #3429 Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288

JozefC wrote ...

Anyone know what's the best oil to use for insulating stuff apart from mineral oil?
I will be needing it for my Quad MOT Stack sometime.

If you are looking for the "best" dielectric oil, then "Shell Diala AX" is what you want. That is the type of oil that I use when I rebuild dental X-ray heads. A good alternative is Exxon Univolt N61B, but I haven't used that brand in many years, and I used it only because Diala AX was not available at the time.

Either of these industrial oils are fairly expensive, and they may only be available in large quantities (I buy it in 55 gallon drums. A drum will last me about a year). I have seen industrial oil for sale on Ebay in the past, but I don't know if anyone is currently selling it. I will not sell small quantities to anyone (sorry) because it's a big pain in the butt for me to do that.

Oh, by the way.... Most dielectric oils absorb atmospheric gases and water vapor like a sponge! Therefore, you want to place it under a good vacuum for at least a few hours to purge the gas and water vapor. It will become a much better insulator if you do that! Then you must hermetically seal whatever housing that you place it in because it will immediately start to suck up water vapor and gases from the ambient air if you do not seal it.

Xray

Kiwihvguy

Thu Dec 30 2010, 07:03AM

Registered Member #3395 Joined: Thu Nov 04 2010, 08:42AM
Location: Christchurch, New Zealand
Posts: 193

Are any of those oils volatile?

Xray

Sat Jan 01 2011, 06:36PM

Registered Member #3429 Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288

JozefC wrote ...

Are any of those oils volatile?

ALL oils are volatile given the right conditions of temperature and other factors. but these industrial dielectric oils have additives that raise their flash-point, making them less likely to combust during a serious electrical malfunction. Go ahead and Google "Shell Diala AX" and "Exxon Univolt N61B", and you will find their MSDS sheets among the list of websites that pop up.

radhoo

Sat Jan 01 2011, 07:08PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

Patric wrote ...

I have very good experience with paraffin, it melts at 52Â°C.

paraffin goes well only up to 40-50KV . It can also develop small cracks that allow air to get close to the hv terminals, not very good.

for very high voltage mineral oil is the way to go, not paraffin. after the oil is added, ideally a pump should be use to suck out any air left in the container.

Kiwihvguy

Sat Jan 01 2011, 10:05PM

Registered Member #3395 Joined: Thu Nov 04 2010, 08:42AM
Location: Christchurch, New Zealand
Posts: 193

Yeah, I wouldn't use paraffin because any MOT can overheat and melt the wax without a ballast to limit the current. Not good. I can't seem to see anywhere to buy mineral oil which is a pain so I might just have to use corn or vegetable oil for the time being...

1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob