Barrier Fluid (Oil or Water not permitted)

[Milkboy]

I need a barrier fluid for a back to back seal.

I cannot use water or an oil (mineral or synthetic)

Im considering Propylene Glycol and Propanol.

Can Propylene Glycol be used 100% i.e. not part of a 50.50 mix with water?

TIA


-
Milkboy

 

[JJPellin]

Either Ethylene Glycol or Propylene Glycol could be used at 100% strength. We would not normally do this (very cold environment) since this results in a higher freezing point than a 50/50 mix. There are other lubricants that are not strictly oils. We use a glycol based lubricant in some flooded screw compressors in a process that cannot tolerate traditional oil. I believe they are sold by Exxon/Mobil. We use silicone based lubricants in some small injection pumps. The main concerns would be to find a lubricant that won't gel up at the lowest temperatures you expect to see and won't oxydize at the highest temperatures you expect to see. Beyond that, a lower viscosity would probably result in longer life. Then of course the elastomers and faces must be compatible with the lubricant.

 

[longeron]

I've heard some bad things about using Propylene Glycol in greater ratios than 50% with water, something about how the buffer fluid tends to become too viscous...

There are some other options. Fluorolube is another I've seen in use, awfully expensive but effective.

Could you use a gas seal instead of a wet tandem or pressurized seal in this application? Even a dry running containment seal with an inert (N2) purge might do the trick.