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RE: Cable pulling lubricant



Donna Chen (DCHEN@EAD.CI.LA.CA.US) asked:  

	> We are looking for an electrical cable pulling lubricant.  The
application is
	> for horizontal subgrade electrical cable.  The cable is plastic
coated and has,
	> through time, become attached to it's outer metal conduit.
Kerosene works
      > well, in freeing up the cable so that it can be pulled from the
conduit. 

Donna -- 

I admit ignorance of what's been tried before in this application, but it
occurs to me that rather than using a lubricant per se, it might be possible
to find another means for freeing the cable from the conduit.  One
possibility might be to take advantage of differential thermal expansion, by
flooding the conduit with either hot or cold fluid (assumedly cheap, inert
gas, such as nitrogen).  This would cause cable and conduit to expand or
contract to different extents, and likely free up the cable.  I'd suggest
starting out cold because it's easier to generate (e.g., a bottle of LN2 or
rapidly depressurized gaseous Nitrogen).

I suspect this might work best on modest lengths of conduit since it really
only addresses the "stiction" component of the problem and not the dynamic
friction that occurs during regular cable pulling operations.

I guess the proof is in the testing, but if it worked, it would permit a
"chemical free" solution to the problem (and avoid the accumulation of
dirt/dust that might accompany the use of something like an oil-based
approach).

Hope this helps.  Let me know what happens if you try it.

Scott

Scott Butner (rs_butner@pnl.gov)
Senior Research Scientist, Environmental Technology Division
Pacific NW National Laboratory
4000 NE 41st Street, Seattle WA  98105
206-528-3290 voice/206-528-3552 fax
http://www.seattle.battelle.org/P2Online/
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