Comments about Oil Mist Filters and Direct Exhausting of Vacuum Pumps to the
Outside
Taken from a posting on the Microscopy Listserver sponsored by the MSA
(Microscopy Society of America).
Question asked by:
Ritchie Sims Ph D
Microanalyst
Department of Geology
The University of Auckland
Private Bag 92019
Auckland
New Zealand
E-mail: r.sims@auckland.ac.nz
Question:
Hi, We need to build an exhaust system for our oil pumps. The reason is
the carcinogenic nature of the pump oil and therefore the exhaust.
Since these pumps are used as backing pumps for systems that do not emit
any other hazardous gazes, replacing these pumps with compact dry pumps
seems to be a good alternative. However, scroll pumps emit graphite and
we do not want to have that in the atmosphere either. I like a piston
pump made by Leybold, the Ecodry M, which is advertised to have very low
particle emission. Does anybody have experience with this pump or have a
suggestion for a zero emission dry pump.
Are you sure the exhaust vapor from a rotary pump are carcinogenic?
Granted, it may not be pleasant or healthy, but as I understand it these
oils are just aliphatic hydrocarbon mineral oils, and they're not
carcinogenic, are they?
An oil mist trap can clean up the exhaust to the stage where it will bother
no-one, particularly if discharged to out-of-doors.
Answered by:
John Bozzola, Ph. D.
Southern Illinois University
Carbondale, IL USA
E-mail: boz5099@verizon.net
Good question. It is generally accepted that long term irritants (even at
low levels) can be carcinogenic. For example, a jagged edge of a tooth can
cause an oral cancer due to constant irritation. Oil mists (while not
carcinogenic per se) can irritate the lungs and cause pneumonia or lung
inflammation. Organo-metallics
(and perhaps by extension, used pump oils) are known carcinogens. Used
motor oil, for example, since it contains organo-metallics, is considered a
low level carcinogen. I am uncertain (but suspicious,however) if used synthetic
oils are similarly carcinogenic.
Microscopists can spend many hours in a room with a vacuum pump. Over a
period of years, well ...... let's just say that it's worrisome. In our
facility, we exhaust the oil mist from our pumps outside the building where
it condenses on the roof of the building and is ultimately washed by rain
into the soil. Not ideal, but the oil is
diluted by water and can be broken down by microbes over time rather than
being concentrated in one's lungs.
Many years ago, I evaluated an exhaust filter that trapped over 99+% of the
oil mist and returned it to the pump. However, after I placed a Petri dish
with distilled water in the room, I could observe (by eye as well as under a
stereomicroscope) tiny droplets of oil landing on the water surface and
spreading out to form an "oil slick". That's when I decided to exhaust to the outside.
Maybe the risk of lung cancer is low but why take the chance?
John Bozzola
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Tuesday September 30, 2008
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