Conductivity Data of Hydraulic Fluid 2

[tc7]

Can anyone advise on where I can find conductivity data and dielectric strength data of hydraulic fluids (Mil-h-5606 and Mil-PRF-83282). The specification documents do not cite this information. I need this data in connection with a static charge problem we are experiencing.

Thanks if anyone can help.
Tom

 

[ecclestone]

Hydraulic oils are not normally rated for dielectric strength.Your supplier for your mil spec products should be able to assist,assuming you are purchasing from the majors.
Usually transformer oils are so rated,these are high quality mineral oils, with anti-oxidants and are absolutely uncontaminated with any moisture and packed under stringent conditions,new drums etc etc. a typical electrical strength figure for such a product is 40kv. with a closed flash point of about 140oC. Typical transformer oils are similar to hydraulic oils in all respects.

 

[25362]

These would probably be synthetic polyalphaolefins (PAOs). Undoped clean oils would have dielectric constant values of around 2, and specific conductivities in the range of 10^-16 to 10^-18 mho/cm.

Their specific conductivity depends on the contaminants (water, additives, metals, etc.) they may have.

The values for water would be 80.4 and 5.5[×]10^-6, respectively.

The static relaxation time for charge to dissipate off a clear paraffinic oil having those characteristics would then be:

[τ] = (8.85[×]10^-14)(2)[÷](10^-17) = 17700 s = 4.9 hours​

For water alone it would be:

[τ] = (8.85[×]10^-14)(80.4)[÷](5.5[×]10^-6) = 1.3[×]10^-6 seconds​

My approach to the issue is the same as ecclestone's: ask the supplier for the relevant information.

 

[tc7]

To ecclestone and 25362-
My first recourse was to contact the recent suppliers and neither Exxon-Mobil or Royal Oil has the data I am searching for. I am making arragements for volume resistivity and dielectric tests with a local lab for comparison purposes.

What is the standard test to determine Specific Conductivity?
And 25362- thanks for posting those equations, what source book may I find these in ( by the way I am not a chemist and I don't have access to a good chemist, so thankyou very much for your help).
Regards,
Tom

 

[25362]

tc7

The formulas can be found, for example, in the book by Crowl and Louvar: Chemical Process Safety: Fundamentals with Applications. Prentice Hall.

Good luck.