Managing sumps & bacterial contamination of metalworking fluids - latest information
This information will help employers (including the selfemployed) comply with the Control of Substances Hazardous to Health Regulations 2002 (COSHH), as amended, to control exposure and protect workers’ health. It is also useful for trade union safety representatives. It covers the points you need to follow to reduce exposure. It is important to follow all the points, or use equally effective measures. Fluid systems that contain water or watermixes can become highly contaminated with harmful bacteria. Mists from these are more likely to lead to asthma and other lung diseases. See www.hse.gov.uk/metalworking
Metalworking Equipment Management
✓ Cover sumps keep them free from:
■ accumulations of swarf or fines; and
■ food, teabags and urine etc.
✓ Minimise leaks of tramp oil (hydraulic, lubricant, gearbox oil) into the sump. Remove tramp oil by skimming, by coalescers, or manually.
✓ Maintain and clean the system in accordance with the machine tool supplier’s instructions. You may also need fluid specific advice from your supplier.
✓ Measure the sump fluid temperature regularly and record your findings. Consider cooling the fluid if its temperature rises significantly above the workroom temperature.
✓ Eliminate any dead end lines in the fluid system. Maintenance examination and testing Fluid quality of watermix fluids
✓ Check input water quality.
✓ Check for bacteria. One way of doing this is dip slide testing.
✓ Every day check the fluid appearance. Are there any reports of an unusual odour?
✓ Regularly check that tramp oil is less than 2%. Get advice from your fluid supplier on a suitable measurement method.
✓ Keep fines and dissolved metals within control limits. Well managed sumps typically have fines below 100 mg per litre of fluid – 100ppm. Get advice on condition monitoring from your fluid supplier.
✓ Measure the fluid concentration (refractometer) and pH every week.
✓ Follow your suppliers’ recommended levels of fluid concentration and pH.
✓ Ask your supplier for advice regarding measurement of biocide concentration.
✓ If you need to add biocide, choose a point of high turbulence ensure complete mixing.
✓ Decide what precautions you need to take before approaching machinery and for handling biocides Caution: Never overdose with biocide for routine use. Machining with metalworking fluids MW5 Special Dip slides
✓ Take dip slides once a week.
✓ If you want to reduce the frequency you need to demonstrate that your controls are effective.
■ dip slide test records; and
■ concentration and pH test records.
✓ Only a ‘competent person’ can advise on changes and recommend new testing intervals, eg priority being given to more vulnerable systems.
✓ Stir the sump before testing, to avoid tramp oil coating the slide.
✓ Use a slide incubator to keep the temperature for developing slides the same all year round.
✓ Incubate the slide at 25ºC for 48 hours, or follow the slide supplier’s instructions. Results from dip slides
✓ If you find only reasonable or poor control, investigate and take action. Control is defined as:
■ Good control less than 10 CFU/ml (1 000 colonyforming units per millilitre of fluid). No further action is required now.
■ Reasonable control between 103 and 106 CFU/ml. You may need to clean the system, or change your biocide regime. Get advice.
■ Poor control more than 106 CFU/ml. Act immediately. This normally means draining and cleaning.
✓ Or take any other measures which are equally effective. Records
✓ Keep records of all tests for at least five years.
✓ Keep dip slide records in graph form. This makes it easy to spot gradual changes and to put in place systems to help you dose when necessary see free download.
■ Your fluid supplier, as a member of the United Kingdom Lubricants Association (UKLA), can advise you on safe application of metalworking fluids. The UKLA can be found at www.ukla.org.uk.
■ HSE priced and free publications can be viewed online or ordered from www.hse.gov.uk or contact HSE Books, PO Box 1999, Sudbury, Suffolk CO10 2WA Tel: 01787 881165 Fax: 01787 313995. HSE priced publications are also available from bookshops.
■ See www.hse.gov.uk/metalworking.
■ For information about health and safety, or to report inconsistencies or inaccuracies in this guidance, ring HSE’s Infoline Tel: 0845 345 0055 Fax: 0845 408 9566 Textphone: 0845 408 9577 email: firstname.lastname@example.org or write to HSE Information Services, Caerphilly Business Park, Caerphilly CF83 3GG.
■ Contact the British Occupational Hygiene Society (BOHS) on 01332 298101 or at www.bohs.org for lists of qualified hygienists who can help you.
■ Envirowise at http://envirowise.wrap.org.uk.
■ Look in the Yellow Pages under ‘Health and safety consultants’ and ‘Health authorities and services’ for ‘occupational health’.
■ Also see www.nhsplus.nhs.uk
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