• A: Yes, the HSE requires employers to minimise exposure to all forms of metalworking fluid – both liquid and mist, in order to comply with COSHH (Control of Substances Hazardous to Health) Regulations. There is currently no Workplace Exposure Limit (WEL) for oil mist particles – the previous TWA (time weighted average) limit of 5mg/m3 was withdrawn in 2005 following an outbreak of respiratory illness at an automotive plant with airborne oil mist under this limit. Employers are currently required to minimise oil mist levels to ‘as low as reasonably practicable’ (ALARP).

    The HSE recommends controlling exposure by using effective LEV (local exhaust ventilation) – all aspects of which should adhere to HSG258 ‘Controlling airborne contaminants at work’:

  • A: Filtermist uses the following calculation to work out which is the best unit size for each specific application.

    Width (of enclosure) x Length x Height less volume taken by the internal equipment and configuration (e.g. Turret or Chuck or Slant Bed) = volume of space to be extracted. This is then multiplied by the number of air changes required per minute x minutes in an hour for air volume requirement.

    Filtermist generally uses 6 air changes per minute as the standard calculation.

    Example: 2.5m (W) x 1.5m (D) x 1.75m (H) - (less) 20% volume = 5.25 m³ (Void) x 6 (Air Changes) x 60 (Minutes) = 1890m³/hr unit required = FX6002

    Having seven oil mist filters in the Filtermist range means we can specify a unit with the airflow closest to your specific requirements.

  • A: The number of ‘air changes’ refers to the number of times the air is cleared in the machine enclosure per minute.

    Reasons for a lower number of air changes (i.e. 1 to 3) could be because the machine cycle is longer than average which means it isn’t necessary to change the air so frequently.

    In all cases, the unit should achieve a negative pressure within the machine enclosure which prevents any oil mist egressing from the cabinet.

  • A: The extraction unit will always take a period of time to clear the cabinet, no matter what the air flow is. You can introduce more air changes to reduce the delay time, however there is a limit. Over extraction creates its own set of issues which can include poor filter life and filter bypass which can be costly and inefficient.

    Accurate clearance times will vary depending on the application and can be established using a smoke test.

  • A: Afterfilters provide a final filtration stage to capture any smaller particles which may not be filtered out in the initial filtration stage. This can include oil smoke and submicron oil mist particles.

  • A: AFB afterfilters have a higher efficiency rating than AFA afterfilters.

    AFA afterfilters are classified as F8. The F8 rating in EN779:2012 means filters are 90-95% efficient at removing particulate matter with diameters of 0.3 μm (micron) or less. Filtermist’s AFA afterfilters have been proven to remove more than 92% of particles with diameters of 0.4 μm (micron) or less.

    AFB afterfilters are rated to H13 which means they are classed as a HEPA filter. To be rated as a ‘HEPA’ (High Efficiency Particulate Arrester) Filter, the filter must remove at least 99.95% of particles a diameter of 0.3 μm (micron) or less.

  • A: In the UK one of the requirements of COSHH (Control of Substances Hazardous to Health) Regulations is that employees should report any defects in an extraction system ‘forthwith’. Using an F Monitor or airflow indicator allows machine operators to easily identify if there are any issues with the extraction system, for example a blockage in the ducting, or filters that need replacing.

  • A: Applications involving high pressure, high spindle speeds and heavy cuts can atomise neat oil and soluble coolant into thousands of submicron particles which can quickly block up traditional filter cartridges, causing unnecessary down-time.

    S Fusion and FX Fusion combine a hi-tech synthetic self-draining media filter with Filtermist’s proven centrifugal technology - offering an effective alternative to other products on the market.

  • A: The decision to invest in a centralised oil mist extraction system, or stand-alone units, relies on various factors. Depending on the nature of the business, each option has its own benefits.

    Factors to consider include:

    • What contaminants needs extracting (oil mist, smoke, dust or fume)?
    • What type of machining cutting fluid are you intending to run with (soluble coolant, neat oil, MQL)
    • Are you intending to use a high-pressure system?
    • What type of process (grinding & Honing, milling & turning, cold heading, quenching)?
    • How many machine tools require extraction and is this number likely to change in the foreseeable future?
    • Are there any open or partially enclosed machines?
    • Is the machine shop frequently re-configured or is it a static production line?
    • How will the system be controlled (inverter driven PLCs)? Damper control valves should be considered to create a smart energy efficient system
    • Should the clean air be returned to the factory or exhausted outdoors?

    The answers to these questions will determine which extraction system is suitable and sufficient to meet your specific requirements and assist in providing a clean working environment.

    This article provides more information: Factors to consider before investing in an air extraction and filtration system

  • A: The nature of grinding applications means there are often larger swarf and dust particles that enter the extraction system. The pre-filter arrests these particles preventing them entering the Filtermist unit. This protects the internal workings of the unit, extends filter life, and reduces service intervals.

    A Filtermist cyclone can be attached to the inlet of the Filtermist unit and the contaminated air will pass through it. The low-pressure area within the separator encourages the heavier particles to fall to its base where they can be easily removed.

  • A: Filtermist units are dual voltage/dual frequency and can be run on 200V or 415V/50Hz or 60Hz. In most cases customers bring a protected supply close to the machine for our Installation Engineers to make the final connection. On selected machines, Filtermist engineers are trained to take a supply from the machine electrical panel.

  • A: Filtermist uses DustTrak Direct Reading Aerosol Monitors (DRAMS) to take indicative readings of the volume of different sized particulate matter at various test points around machine tools. The results are intended to be used as an indicator of whether the machine tool has sufficient extraction fitted. If the particle loading at certain points is high, it is likely that control measures need implementing or existing controls need reviewing. The readings can also be used to help determine what type of extraction is required as the particulate size and the volume of particles both have a bearing on the most suitable type of filtration for that specific application.

  • A: There is currently no Workplace Exposure Limit (WEL) for oil mist particles – the previous TWA (time weighted average) limit of 5mg/m3 was withdrawn in 2005 following an outbreak of respiratory illness at an automotive plant with airborne oil mist under this limit. Employers are required to minimise oil mist levels to ‘as low as reasonably practicable’ (ALARP) through the use of effective control measures.

    This HSE research report provides more information on the monitoring of water-miscible metalworking fluid (MWF) mists: www.hse.gov.uk

  • A: HSE publication EH40 contains the list of workplace exposure limits for use with the Control of Substances Hazardous to Health Regulations 2002: www.hse.gov.uk

  • A: Filtermist oil mist filters can be supplied with a carbon wrap to help remove unwanted odours. Selected Absolent units can be fitted with an activated carbon filter cassette or independent activated carbon cell.

  • A: Yes, one Filtermist unit can be used to extract from multiple machines dependent on air flow and ducting requirements.

  • A: Different types of coolant will generate different types of mist particles. For example, applications using neat oil tend to generate large volumes of submicron particles which require a higher filtration efficiency than particles generated in applications using soluble coolant.