COVERS AND GUARDS
Chains, motors, gearboxes, sprocket wheels, etc. must be guarded or covered for the following reasons:
- • To prohibit injury to operators during inspection, cleaning, disinfection, and maintenance.
- • To protect difficult to clean machine components (e.g., drive parts) against contamination by food debris.
- • To prevent liquids (e.g., cleaning solutions, condensate) from intruding into water-sensitive machine components.
- • To prohibit damage to machinery components.
- • To protect the food product from contact with drive parts such as lubricated chains and sprocket wheels.
However, the requirements of guarding or covering machinery to ensure safety in operation may easily conflict with the recommendations of EN 1672-2 as well as other hygiene requirements. By their nature, covers and guards may compromise food safety, unless considerable care is taken in their design, construction, installation, and maintenance.
Good hygienic design and a stringent cleaning/disinfection regime can solve many problems. Covers and panels must be designed so as to prevent entry and/or accumulation of soil and liquids. Upturned sections, that may provide a tray in which dirt and liquids may accumulate, are not allowed. To ensure good drainability, covers must be contoured to avoid horizontal surfaces and provided with an angle of 5 degrees away from food areas. Where horizontal surfaces can’t be excluded, avoid panel joints and provide overlap where possible. Reduce exposed fixings to a minimum. Covers on their own— although practical—can often make cleaning more difficult. Wherever covers are used around drive parts such as chains and sprockets, they should be easily removable to provide access for cleaning, either by opening or unhinging them (Moerman et al., 2005).
Totally removable covers or cladding are not recommended as they may not be put back or they may be damaged during removal. Without covers, operators in the environment of the process equipment and exposed food products are at risk. Where possible, hinged covers that pivot outboard should be used. But use as few hinges as possible, and use concealed hinges with
FIGURE 6.55 (A) Continuous and piano hinges are not allowed (Frank Moerman, © 2016).
(B) From left to right: block hinges lift-off type, pin hinges with removable pins or concealed hinges should be used. An alternative could be a hingeless cover fixed by means of two small screws at both sides. First and second photo, courtesy of Heinen Freezing GmbH & Co. KG; third photo, courtesy Den Rustfri Stalindustris Kompetencecenter; fourth photo, courtesy IQF Frost AB; Frank Moerman, ©2016.
the least number of parts. In view of cleaning and disinfection, continuous and piano hinges (Fig. 6.55A) are not allowed. Block or pin hinges are a possible option but should have removable hinge pins or be of the lift-off type (Fig. 6.55B). Sliding covers are not recommended and if they are used, tracks and guides for covers must be designed to minimize retention of food particles, condensation water, spillage, and soil. As an example, the grooves shall be rounded. For small covers, a “D” handle mounted to the cover is acceptable (Fig. 6.56) (Moerman et al., 2005).
Clear plastic covers (Fig. 6.57) should be made of shatter-resistant material. Polycarbonate is especially prone to cracking if not installed properly (e.g., lack of room for expansion). To maintain the clarity of the transparent material over the life of the equipment, it must be resistant to cleaning agents and disinfectants, and—where necessary—hot water and steam. Acrylic and polycarbonate should be at least, respectively, 12 mm and 5 mm thick. Transparent covers preferably should be mounted unframed; however, for large covers a frame is often required. The frame should be mounted spaced away from that transparent cover and should be provided with a handle or rail to hinge open the cover without putting
FIGURE 6.56 Products transported by a conveyor belt are protected from the environment by means of covers provided with “D” handles at their sides. Courtesy of Bay State Industrial Welding & Fabrication, Inc.
FIGURE 6.57 Clear plastic covers/guard. Frank Moerman, ©2016.
stress on it. Plastic covers should not be used where frequent removal of covers is required (APV Baker, 2001).