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FAQs – Oil Mist

FAQs - Oil Mist

Oil mist nearly always results in oily premises, equipment, and products. Modern metalworking machinery is often controlled by sensitive electronics and production is hampered by unplanned disruptions caused by contaminated controls. Handling equipment and pieces of products coated in a thin film of oil is not an acceptable working practice and definitely not production friendly. Thus, removing oil mist is essential for workplace cleanliness and safety.

Oil mist affects the health of machine operators, disrupts production and settles throughout manufacturing facilities, resulting in dangerous conditions, such as, slippery floors and work surfaces. Nearly all machining operations create oil mist to some extent. Oil mist is the aerosol that is formed when oil is used for cooling or lubricating during the machining of metal and some plastic components. Oil smoke is formed when oil contacts the hot machined surface, vaporizes, and condenses as sub-micron particles.

Prolonged and repeated exposure to oil products can be harmful to health, which means that quality ventilation must be ensured under all working conditions. Oil emulsions normally contain 90-95% water and the remaining is non-soluble oil. The oil mist consists of aerosols from oil or oil/water emulsion. Mineral oil-based metalworking fluids are known as neat cutting oils or straight oils. Emulsions normally contain a number of undisclosed additives.

Oil mist is created when metal working fluids (MWF) become aerosols or mists as a result of heat and/or the machining process itself. There are four types of MWF’s: Straight & soluble oils and synthetic & semi-synthetic fluids . Many of these fluids contain additives. Additives may include, but are not limited to: corrosion inhibitors, emulsifiers, de-foaming agents, stabilizers and sulfur or chlorine based compounds.

Breathing ailments, cancers and skin conditions have been proven to be caused by these mists with prolonged exposures exceeding OSHA thresholds. Nitrosamines, many of which are known carcinogens, can form in stored MWF’s as well as contributing to microbe growth. OSHA has set 5 mg/m3 over an 8-hour time period as it’s max exposure limit value.

There are several methods of collecting oil mist.

  • Ambient oil mist collectors are designed to recirculate the air though several air filtration devices suspended from the ceiling. The media is either electrostatic or polypropylene, designed for the coalescing of mist. Removal efficiencies can be upwards of 95%, however establishing and maintaining an air pattern is critical to its success.
  • Machine mounted mist collectors can be placed directly on the machine, allowing the collected coalescing mist to drain back into the machine. They serve only the machine they are mounted to.
  • Central oil mist collection systems are ducted from each machine back to a central collector. The central collector will utilize a mechanical separation prior to the media because the volume of mist collected is greater. Each area that is producing oil mist is source captured and sent back to the central collector.


Once we’ve decided the best mist collection method, we must consider the use. Drilling, lathes and screw machines will generate much less mist than stamping, roll forming and cold headers. Typically, the higher the heat the smaller the particle size and increase in aerosol formation.

Whether a central mist collection system or ambient mist collection system the design is as critical as the product selection. A central mist collection system with too much draw will flood the collector with coolant. The duct system needs to be properly sealed using the right duct materials, so it doesn’t leak. Sizing the fan and airflow all play a vital role that should be chosen by someone qualified in industrial ventilation design.

Oil mist ventilation is a complicated science as the oil must be removed from many different source types. Each source type creates a unique challenge and should be designed by a specialist in air quality engineering.

Anyone who produces coolant mist and smoke knows the problems that arise if you don’t effectively capture and filter it. From oil puddles on machinery and floors to the blue haze and odors across the plant, coolant mist and smoke become maintenance issues and safety & health risks. Clean Air mist collectors provide solutions to these issues, offer longer filter life, and better efficiencies.

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