Gel dryer / pump corrosion - New Pumps from Edwards

Tony Hodge tph at
Fri Jun 17 03:05:49 EST 1994

Subject: Gel dryer / pump corrosion
From: Paulo Magalhaes, pamaga at
Date: Thu, 16 Jun 1994 14:28:11 GMT
In article <CrHuv0.6zq at> Paulo Magalhaes,
pamaga at writes:
>Hi all!
>A couple of questions concerning "small" problem we're having.
>Recently we found that the pump used with our gel dryer (a so-called
>"one step oil pump"), got corroded and eventually stopped working.
>The manufacturers claim that it must be something that gets into the
>pump (the oil, in spite of regular changes, was *very* brownish).
>Perhaps of interest, there was a "cold trap" installed between the
>pump and the dryer.
>Anyway, before buying a new pump and perhaps running into the same
>problem, we'd like to know if someone out there has experienced
>similar problems.
>Please email your opinions, since I don't normally read this
>Thank you for your time.


We are presently evaluating one of a new series of pumps from
Edwards which they believe will be more resistant to corrosion. 
They are the RV series and we are trying an RV5 for drying down
sequencing gels, ie lots of Acetic Acid.  We are NOT using a cold
trap and the pump has an Outlet mist filter to trap oil droplets in
the exhaust.  We have found that the exhaust does need to be vented
to the outside or a fume cupboard but after some months of running
the pump still pulls an extremely good vacuum.  A representative
from our local supplier and one from Edwards are overseeing the test
and will soon take the pump away to dismantle it and inspect for
corrosion.  These pumps have simple controls for high vacuum or high
throughput applications.  The representatives are currently
suggesting 3 monthly oil changes.

When the pump has been dismantled and examined we are considering
putting together a publication of some sort in the laboratory
equipment press to report our findings but watch this newsgroup for
further developments.

BTW the nearest Edwards office I know of to you would be:

Division of BOC NV/SA
Rue du Bosquet 1
B1348 Louvain-La-Neuve

Tel.   32 0 10 45 10 71
Fax.  32 0 10 45 61 92

I have no formal connection with Edwards, we are trying out this
pump for our own applications here in the LMB.


Tony P Hodge
Structural Studies Division
Medical Research Council Laboratory of Molecular Biology
Hills Road
CB2  2QH

Phone (0223)  402260

Fax     (0223)  213556

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