I've heard some people talk about cooling a computer by immersing the hardware in mineral oil, and seen a few videos on YouTube demonstrating it. Maybe I'm just overthinking it, but this sounds a little bit hazardous to the user's health.

ISTM that putting a strong heat source inside an open container full of a petroleum distillate product, and then staying in an enclosed room with it for a significant period of time, is a real good way to end up learning why huffing gasoline fumes is generally considered a bad thing. What am I missing? How is a cooling system like this safe?


I don't have hard numbers, but the evaporation rate of mineral oil is, to my understanding, VERY low (as opposed to say, gasoline, which has a pretty high evaporation rate, even under normal temperatures, or even water). Heating it up by the amount put off by a PC doesn't change that very much, so the amount of evaporation stays very small, and you don't end up with a problem.

If you are really paranoid, but want to get into immersion cooling, then you should find yourself a source of de-ionized water. That's water that's filtered so heavily that there's nothing conductive in it, and thus it's safe to immerse electronics in it. (If memory serves, the original Cray computers were cooled in this way.)

  • The problem with deionized water is that unless the enclosure is 100% airtight that you'll probably get impurities from air circulation over top of the water. (I have no idea what time scale it would take for this to become a problem, but it's there.) – Shinrai May 23 '11 at 18:18
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    You'd also have evaporation issues, I'd think. I imagine that working with a deionized water system would sort of require easy access to de-ionized water for flushing, topping off, etc, etc. so it's probably not the best plan for a hobbyist. – Michael Kohne May 24 '11 at 10:41
  • Oh, yeah, duh. I didn't even think about the obvious problem >.< – Shinrai May 24 '11 at 14:07

The same way that you can use oil to lubricate an engine without killing the driver:

  • It requires REALLY high temps to ignite
  • It's in a closed system where the fluid recirculates
  • I'm not talking about igniting it, but about hydrocarbon fumes getting out into the air that the user is breathing, which is hard on your brain. – Mason Wheeler Aug 4 '10 at 17:50

I also agree that mineral oil does not evaporate at room temperature and at higher temperatures evaporation would be somewhat negligible if any. The boiling temperature for mineral oil is about 650 F and obviously is lower than its flash point. As you know, this is well above the operating temps of a pc and the oil will likely never reach that temperature when only used at this capacity.

However, mineral oil does have a relatively high absorption rate and I suspect that this may be why some people believe that it evaporates. This is actually one of the benefits of it. You can test it for yourself however and leave a container of it sitting and watch how quickly it evaporates. Typically the higher the temperature, the more the substance will evaporate.

In any case, if you did use mineral oil to cool your computer, evaporation would be noticeable once the oil level drops. You can tell how much the oil has evaporated by the amount left over time. Although there have been reports of oil loss by a wicking effect through cables immersed in the fluid. (Something to watch out for.)

As an example of how safe it is as compared to kerosene or some other petroleum distillate product...although I personally don't use it on my skin, mineral oil is basically baby oil with fragrance and other minor things added. It is considered safe for skin application. The simplest baby oil will be mineral oil and a fragrance of some sort. Certain brands may add other items just as any other product, but the main ingredient is mineral oil.


Mineral oil is safe when it comes to people. Look outside of PC hardware and you'll see it has a wide range of uses, including as a laxative. Flammability wise, it is virtually inert unless you plan on super-heating it and since it's an oil, it is very slow to evaporation.

Mineral Spirits are the more "industrial" version of mineral oil. The spirits are not an ”oil" and will evaporate quickly. However, even mineral spirits are safe to handle in controlled amounts and the fumes and no worse than a can of cooking spray. They are widely used in furniture dry cleaning services.

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