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DI water, it wont ever be a good or practical dielectric
To anyone interested:
The idea of ultrapure water, DI water, 18 megohm water or whatever, being
used as a dielectric is crazy. First of all, 18 meg water only really
exists right out of the purification system in which it was produced. Water
is such a great solvent that it easily contaminates itself with traces of
ions, and loses its 18 meg quality very quickly. You can take 18 meg water,
put it in a glass container for a few minutes, and the conductivity will
have measureably increased. The bottom line is that ultrapure, 18 meg
water, is expensive to produce (our water system here for cell culture media
production, cost over $10,000.00) and is extremely difficult to keep pure.
Yes, in a teflon conductivity cell, the resistivity of nano pure water is 18
megohm/cm^2, but try taking this water and filling a HV capacitor or a
distribution transformer with it and see how long those devices last. My
guess is less than a few tenths of a second. Also, there is NO additive you
can add to water to make it less conductive!! Get some good dielectric oil
like Diala AX or the like and you will live long and prosper. Hope this
helps.
Eric
edavidson-at-icva.gov