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

E-mail at b.reynolds@blaser.com

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The Oil Baron Bulletin is not affiliated with Blaser Swisslube Inc. or its subsidiaries