How to design machine guards for the food and beverage manufacturing industry
Steve Allen, a Member of standards committee BSI MCE/3 (Safeguarding of machinery), a Certified Machinery Safety Expert and National Sales Manager at Procter Machine Safety, presents a guide to the special requirements for machine guards used in the food and drink manufacturing industry.
Data from the Health and Safety Executive (HSE) for 2018/19 relating to injuries in the food and drink industry show there were two fatal injuries and 3150 non-fatal reported injuries in this 12-month period. Moreover, the figures of 1027 reported injuries per 100,000 employees for the food manufacturing industry and 438 per 100,000 for the beverage manufacturing industry are some of the highest in the manufacturing sector, which averages 468 per 100,000, while the ‘all industries’ rate is 254 reported injuries per 100,000.
Thanks to a longstanding initiative from the HSE and the food and drink industries, there was a 60 per cent reduction in reportable injuries from 1990/91 to 2013/14. Nevertheless, the latest statistics show there is still scope for improvement. This point was also emphasised in the ‘Recipe for Safety’ guide, which was revised and updated in 2015 by the HSE and a working group of the Food and Drink Manufacture Health and Safety Forum.
One-third of all fatalities in the food and drink industries relate to plant and machinery; no other single cause accounts for as many deaths. Furthermore, a significant proportion of non-fatal injuries are also due to machinery. HSE analysis shows that in 75 per cent of non-fatal injuries involving machinery there was no guarding or it was inadequate, and 25 per cent of injuries occur during cleaning. Guarding design is therefore crucial in the battle to improve safety and these figures highlight the importance of considering all interactions with the machinery, not just normal operation – for example, start-up procedures, in-shift cleaning, machine resetting for product changeovers, clearing jams, reel changes, routine maintenance and troubleshooting.
Bear in mind also that machinery is encountered in many areas within the food and drink manufacturing industry. As well as the core production equipment, there will be packaging systems, palletisers, conveyors and, in larger state-of-the-art facilities, automated warehousing. All of the machinery needs adequate guarding if it is to be safe.
Something that is not always appreciated, however, is how guarding for food and drink machinery differs from guarding for other types of manufacturing equipment – and it is not just a question of specifying stainless steel and sealed interlock switches.
How to manage health and safety
One of the characteristics of the food and drink industry is that frequent access is required to assist product flow, clear blockages or spills, and carry out cleaning. Moreover, there are two distinct categories of cleaning: in-shift cleaning that essentially takes place as part of the production process or at product changeovers, and more thorough end-of-shift cleaning. Whereas manufacturing production equipment in other industries can typically be fitted with removable guards to provide access to danger zones for cleaning during shutdowns, food production equipment guards must allow for rapid yet safe access for in-shift cleaning, assisting product flow, clearing blockages, or any other tasks that could be considered part of ‘normal operation’.
Another differentiator between food and drink and other industries is the nature of the hazards encountered. While most manufacturing equipment hazards relate to powered motion and electric shock, the food and drink industry has these but with the addition of hazards relating to stored energy. These include hot surfaces and parts (including product), steam, hydraulic systems, pneumatic systems and pressurised atmospheres. Very cold items are also hazardous, as are vacuums, sharp blades, dust and noise emissions. The design of guarding and the associated interlocks therefore needs to take account of these, perhaps incorporating time delays or temperature sensors to allow items to cool down (or warm up), or interlocks to ensure pressures are equalised before access can be gained. In some cases restraining catches may be required on doors covering pressure zones so the doors will not be blown wide open if they are unlatched prematurely.
With regard to the design of the guards themselves, fixed guards should be avoided because of the frequent access required, while hinged guards are preferred to removable guards so as to avoid the guards being refitted incorrectly. Again, the requirement for regular access implies that the guards should be designed to be opened as quickly and easily as possible, but without compromising safety. Opening guards must, of course, be interlocked so the machine will not restart unless the guards are in place.
Stainless steel is the preferred material for guarding, taking care to specify the correct grade to suit the foodstuffs being processed and the cleaning agents that will be used, both of which can be extremely corrosive. Aluminium, clear polycarbonate and other plastic and plastic-coated components can also be used where appropriate.
Ledges, crevices and other ‘bug traps’ should be avoided, and all box sections closed; corners should be radiused wherever possible. Both the guarding framework and the guards themselves must be suitably robust to cope with the frequent opening and closing, remembering that guards must not be overly heavy because this could contribute to operator fatigue. Interlocking devices need to be fully sealed, easy-clean devices such as coded magnetic safety switches, and it should be noted that sealed high-integrity light curtains might prove to be an appropriate alternative under certain circumstances where frequent, rapid access is required.
There are two other aspects of guarding that are particularly applicable to machinery for the food and drink industry: dust/fume extraction and noise reduction. Dusts and fumes can be particularly hazardous to health or even explosive; these should therefore be removed and a guarding system will often be designed to incorporate extraction. If noise is a problem, suitable guarding can reduce the noise emitted to an acceptable level. The Control of Noise at Work Regulations 2005 came into force in April 2006 and, by law, employers must assess and identify measures to eliminate or reduce risks from exposure to noise so as to protect employees’ hearing. A free PDF booklet reference HSG232 (second edition, published 2013), is available from the HSE, ‘Sound solutions for the food and drink industries – Reducing noise in food and drink manufacturing.’
The UK has now left the European Union and the transition period ended on 31 December 2020. With the UK outside the EU’s free trade area, the UK and EU have agreed a new trading relationship. Machine builders exporting to the EU must continue CE marking but, here in the UK, CE marking has been replaced by UKCA (UK Conformity Assessed) marking. While the process of UKCA marking is essentially the same as for CE marking, documentation needs updating to refer to UKCA marking, and standards listed on the Declaration of Conformity or Declaration of Incorporation should be prefixed with BS to show they are British Standards. Furthermore, the UKCA mark needs to be displayed on the machine instead of the CE mark. As with CE marking, the UKCA marking system for machinery also covers safety components and, in some cases therefore, machine guards need to be UKCA marked.
The simplest way for machine builders to comply with the requirements for UKCA marking and CE marking is to design and manufacture the machine in accordance with pertinent standards; these are referred to as Designated Standards for UKCA marking and Harmonised Standards for CE marking. As far as guarding for food and drink machinery is concerned, the most important standards are:
- BS EN ISO 12100:2010 ‘Safety of machinery. General principles for design. Risk assessment and risk reduction’
- BS EN ISO 14120:2015 ‘Safety of machinery. Guards. General requirements for the design and construction of fixed and movable guards’
- BS EN ISO 13857:2019 ‘Safety of machinery. Safety distances to prevent hazard zones being reached by upper and lower limbs’
- BS EN 1672-1:2014 ‘Food processing machinery. Basic concepts. Safety requirements’
- BS EN 1672-2:2020 ‘Food processing machinery. Basic concepts. Hygiene requirements’
Numerous other standards address the needs of specific types of machinery used in the food and drink industry, ranging from dough mixers and slicing machines to vegetable peelers and pie and tart machines. Other standards focus on particular machinery that is commonly used in other industries but may also be encountered in the food and drink industry, such as palletizers, robots and conveyors.
Indeed, conveyors are worth a closer look in this present article because the HSE has identified that they are involved in 30 per cent of all machinery accidents in the food and drink industries, which is more than any other type of machine. Conveyors are often forgotten about because they are either viewed as integral to other machines – as infeed or outfeed conveyors – or they simply move product or packaging without performing any process as such. The HSE statistics show they can be extremely hazardous, yet most of the accidents are avoidable. We can say this because 90 per cent of accidents involve well-known hazards and 90 per cent occur during normal foreseeable operations such as production, clearing blockages and cleaning.
Conveyor hazards that can be readily designed-out or safeguarded include in-running nips between the belt and end roller, transmission parts, and trapping between moving and fixed parts. As well as providing protection against hazards, conveyor guards can provide other benefits in food and drink manufacturing: covered conveyors prevent contamination of products or packaging, and enclosed conveyors reduce noise emissions – particularly when glass bottles or jars are being moved.
Why workplace machinery is a priority
Clearly machinery guarding for the food and drink manufacturing industry is a specialised area, but one where good design can help to minimise access time and reduce downtime while improving safety. Procter Machine Safety has been designing, supplying and installing bespoke guarding for the food and drink industry for over 30 years, with each project undertaken in such a way as to meet the needs of the customer as well as the latest standards, legislation and HSE guidance. CAD (computer-aided design) and CAM (computer-aided manufacture) ensure the guards are an accurate fit on the machinery and can be installed as quickly as possible. While many of the guards are supplied for new machinery, custom guarding can also be supplied to fit existing machinery such as conveyors and packaging lines; in this case an experienced designer will conduct a detailed site survey prior to preparing drawings for the fabrication team to work from. If required, Procter’s experts can also conduct machine guarding compliance surveys, risk assessments and PUWER inspections.
To discuss any requirements for machine guarding in the food and drink manufacturing industry, whether for new projects or existing plant, please contact Procter Machine Safety by calling 02920 855758 or emailing [email protected], or visit the website at https://www.machinesafety.co.uk