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solvent sinks and P2

There has been some extended discussion of the use of degreasing sinks and
solvents.  The most effective P2 in some cases is to use a solvent with a
higher flash point and lower volatility (not always the same thing!), and to
use 2 or 3 sinks at each location.  The solvents cease producing clean parts
when they get too much grease and oil, along with the dirt, in the solvent.

Using two sinks, one puts clean solvent in the second sink and the used
solvent in the first one.  All parts are washed first in the first sink to
remove as much grease, oil and dirt as possible.  Then they are washed in
the second sink in the clean solvent.  Putting a filter in each sink may
also help extend the life.  When the solvent in the second sink quits
producing clean parts, then the solvent in the first sink is removed for
recycle, the solvent in the second sink is moved to the first, and fresh
solvent is put into the second sink.

At facilities that were changing solvent every 2 weeks, this system has
resulting in changing solvent every 8 to 16 weeks, or a 300 to 700 percent
extension in the life of the solvent, with a reduction in waste generated to
between 15 and 30 percent of the prior usage

In a few cases, use of three sinks is effective.

Labor may object at first to the extra step of rinsing the parts in two (or
three sinks), but the cleaner parts will win almost all over after they try
it a few times.

Putting a foot-pedal operated lid (usually with a spring or hydraulic
assist) on the sink will reduce evaporation of the solvent.  Some shops
leave the circulating pump on so that parts can rinse under the flow with
the lid closed.   Other shops find it effective to have the pump switch on
with the lid opening, operated by the same pedal.

This is simple and works!  I have helped put it in in over 100 shops of
various kinds.

BTW, use of solvent sinks to remove the heavier grease, oil, and dirt,
followed by a citrus or other water-based cleaner, also can reduce the need
to change out both, since the water-based cleaner doesn't get loaded with
grease as fast and the solvent cleaner isn't expected to produce really
clean parts, only to remove the gross amount of grease and oil.

Ralph E. Cooper, Ph.D.
J.D., Class of 1999
Case Western University School of Law
Cleveland, Ohio