Oil Mist & Vapor
Dear
friends,
If
you’ve worked in a machine shop long enough, you might have noticed various
items such as tool boxes, work benches and machine surfaces becoming oily or
sticky. You might even work at a facility where a constant fog hangs in the air
during working hours. Both of these issues have one thing in common – Oil Mist
& Vapor. So where is the mist coming from, but better still, what can you
do about it? In order to know the proper solution to the problem, it’s
imperative that we understand the nature of the problem and how it is being
created. During machining, mist and vapor formation are given off simultaneously
during the metal removal process. The difference in mist verses vapor is the
difference in particle size, with vapor and smoke being <1µm.
The
various mechanisms of mist and vapor formation are the following:
·
Evaporation/Condensation
– Most often produces smoke, due to fluid coming in contact to the hot
work/cutting zone.
·
Impaction
and Centrifugal force – High speed spindles create motion, thus spraying fluid
which impacts part and machine surfaces.
·
Aeration/Entrained
air – Entrained air (bubbles) is released when the fluid is at rest, forming
aerosols.
Not
all mist and vapors are attributed to the fluid; welding fumes, along with
metal dust, common dirt and parts washer mist all contribute to the overall
mist levels in the shop. Mist levels are measured by several methods, both
quantitative and qualitative, using either a personal sampling monitor,
(Quantitative) and/or light scattering instruments, (Qualitative). The OSHA
Permissible Exposure Limit, (PEL) for metalworking fluid mist is 5mg/m3
of mineral oil mist. This is the only statutory limit that has been imposed by
OSHA; however most large manufacturing companies are now following the NIOSH
Recommended Exposure Limit, (REL) of 0.5mg/m3 of total particulate
mass, as a safety measure. High mist levels in the shop can also be directly
correlated to how much tramp oil is in the coolant itself. The higher the tramp
oil load, the higher the mist level. High levels of tramp oil contamination
(>4%) in the metalworking fluid, can lead to an increased level of bio-mass
accumulation. This is due impart to Anaerobic-sulfate reducing bacteria. These
microbes are present in the bulk fluid, and are also thus present in the
mist/vapor which is generated by the aeration and spraying action of the
coolant itself. These bio-aerosols are being linked more and more to the acute
effects of cough and phlegm production, as well as shortness of breath and
bronchitis. These acute effects may lead to chronic lung conditions such as,
asthma and hypersensitivity pneumonitis (HP).
So
what can I do to reduce the mist levels in my shop?
Remove
tramp oils on a consistent basis and keep microbial levels in check and under
control. Practice good housekeeping procedures. Install mist and filtration
collection systems and keep them well maintained. Make sure machine guards are
in place and ensure there’s adequate ventilation. Above all, maintaining your
coolant can go a long way to reducing the overall mist levels in the shop, thus
making a cleaner and healthier work environment for all concerned.
Stay
tuned for more useful coolant related tips, from The Coolant Guy!
Best
regards,
Brett
Reynolds, CMFS
Brett Reynolds, “The
Coolant Guy” works for Blaser Swisslube Inc.
If you would like
more useful information regarding metalworking fluids, or would like to find
out more information about Blaser metalworking fluid products,
Please contact Brett
at 801-722-4095 or via
theoilbaronbulletin@blogspot.com
The Oil Baron
Bulletin is not affiliated with Blaser Swisslube Inc. or its subsidiaries
