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Liquids as insulators

  1. Nov 29, 2008 #1

    I'm looking for an inexpensive liquid, that should be used as an insulator.
    My first pondering was if there is a way of converting water to insulators.

    Thanks in advanced.
    Last edited: Nov 29, 2008
  2. jcsd
  3. Nov 29, 2008 #2
    Distilled water.
  4. Nov 29, 2008 #3
    The reasoning for this, is as you probably know, water is a very good conductor. However, 'Pure' water doesn't conduct at all. So if you go and get some pure H2O then you have a fantastic liquid insulator on your hands.
  5. Nov 29, 2008 #4
    yes, but keeping water pure is another matter
  6. Nov 29, 2008 #5
    What do you mean by keeping it pure?
    If I get pure water, should I keep it some way?

    Thank you both!
  7. Nov 29, 2008 #6
    water is an excellent solvent. don't try to use it as an electrical insulator.
  8. Nov 29, 2008 #7
    Unfortunately, I have to use water as an electrical insulator (or any other liquid). I have to build an electrical circuit in water.
    I'm not dealing with dangerous levels of electricty.
  9. Nov 29, 2008 #8


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    Water only needs a small amount of ions dissolved in it to become conducting, the salt on your skin if you put your hand in it, any dirt or contaminants on the electrodes etc.

    Most oils are much better insulators, they are used in transformers for instance. In the past CFCs were used, Cray famously used a CFC based artificial blood plasma to cool their supercomputers. I think you can still buy Fluorinert ?
  10. Nov 29, 2008 #9
    then you probably want some type of potting/sealant.
  11. Nov 29, 2008 #10


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    Ultra pure water is also called 18MOhm water, that the specific resistivity, but it is very difficult to keep it that pure. Leaving water in contact with air will be enough to contaminate it. You need spcial containers (made especially for that purpose) just to store the ultra pure water. That's not an easy liquid to deal with.
  12. Nov 29, 2008 #11
    Some GPU's and CPU's are inserted in containers filled with oil to maintain the temperature. I'm not sure what kind of oil but you could do some research about it.
  13. Dec 1, 2008 #12
    Oils used as electrical insulators (dielectrics) is an area of expertise for me, as I worked in developing them for about 15 years. Most oils need some additional treatment to remove polar impurities and increase the resistivity, however, something like a white oil (liquid paraffin) would be electrically resistive "as is" without further treatment.

    You should be able to purchase it in small quantities from a chemists shop. Vegetable oils (e.g. castor, or cooking oil) are not really suitable as they are essentially based on esters (they are glycerides) and the polariity of the molecules makes them less suitable as dielectrics.
  14. Dec 1, 2008 #13


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    Plus they are vulnerable to rancidification, so they wil start to stink after some time. That won't happen with mineral oils.
  15. Dec 2, 2008 #14
    This is what you're thinking of:

    Last edited by a moderator: Sep 25, 2014
  16. Dec 2, 2008 #15
    The oil in the You Tube video is a "white oil" - the canister is labelled "light mineral oil - light laxative". That specific one would be medical quality, but assuming you're not going to actually drink any of it, a technical quality one would be fine.

    Marcol 82 by Exxon Mobil (thats the medicinal quality one, they do a technical grade too), or SPC 15 by SIP, or any oil referred to as "WOT 14" (white oil technical) from a chemicals distributor would do.
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