whit3rd wrote:
On Wednesday, October 10, 2012 3:51:16 PM UTC-7, Cydrome Leader wrote:
Phil Hobbs wrote:

The part I've not figured out is why or how does silicone diffusion pump
oil go bad, and why does it have an expiration date on the bottle.

Probably because some silicones are used in medical devices, and
the FDA gets very crazy when they cannot determine expiration
dates. Or calibration dates.

The Dow 704 I have actually says on the bottle "NOT FOR HUMAN INJECTION!".
I even wrote to Dow asking if people shoot up vacuum pump oil, and if so,
why. I never heard back, but was apparently enough of a problem to put
this on the labels in 2003.

It also means some customers will reorder more often. I recall,
however, we loaded our diffusion pump and NEVER thought
of replacement of the silicone oil unless it got too dirty to pump.

How did you determine the diffusion pump was dirty? I'm still not clear on
how you even drain the oil out of the one I have, other than the turn the
entire thing upside down, and hope everything drips out. Do you then wash
it out? Silicone oils are pretty disgusting, and I'm happy the stuff
hasn't crawled out of the pump and all over the place.