HYGIENIC DESIGN OF OPEN VESSELS, CONTAINERS, AND BINS
Interior and Exterior Design of Open Vessels, Containers, and Bins
Appropriately designed and installed open vessels, containers, and bins shall meet the following recommendations (Moerman & Kastelein, 2014):
- • Equipment without bottom outlets must be pivoted (Fig. 6.13) over an angle of at least 93 degrees for fully discharging product and cleaning solution. While fully drainable, contaminants from the exterior of the open vessel, container, or bin (e.g., dirt from casters) may not gain access to the food product being discharged.
- • The vessel, container, and bin tipped for discharge must be designed for improved cleanability. Vessel corners should be well rounded and hinges must allow for maximum cleanability.
FIGURE 6.13 To fully empty containers without bottom outlet, they must tip over an angle of at least 93 degrees. The interior and exterior of the container must be designed to exclude any contamination of the food product when it is drained. Vessel should have well-rounded bottom corners, with hinges designed for maximum cleanability (Lelieveld et al., 2003; Hauser et al., 2004b).
- • Open vessels, containers, and bins with bottom outlets must have their discharge outlet at the lowest level and their bottom shall be sloped (more than 3 degrees toward the outlet). Their corners shall be well- rounded, with a radius equal to or larger than 3 mm (Fig. 6.14).
- • The design of the top rims of product-containing equipment (e.g., open tanks, chutes, boxes) must avoid ledges where product can lodge and which are difficult to clean (Figs. 6.15 and Fig. 6.16A). Open top rim designs must be rounded and sloped for drainage (Fig. 6.16B). If the top rim is welded to the wall, the weld must be flush and polished to provide a smooth surface and the rim must be totally closed. Any holes, therefore, must be sealed by welding or by fitting sealed caps (Fig. 6.16B).
FIGURE 6.14 For good drainability and cleanability, open vessels, containers, and bins used in the processing of food (1) shall have their discharge outlet at the lowest level. Their bottom shall be sloped (more than 3 degrees toward the outlet), and their corners shall be well-rounded. Where food product and cleaning solutions are not allowed to drain, residual soil (2) will be left. Sharp corners (#90 degrees) must be avoided (Lelieveld et al., 2003; Hauser et al., 2004b).
FIGURE 6.15 A badly designed rolled-over part of top rim provides a ledge where product debris can lodge. Don Graham, Graham Sanitary Design Consulting LCC, ©2010.
FIGURE 6.16 Top rims may impart rigidity to the construction. (A) However, a rim with an upper horizontal part provides a surface where debris may collect. When the rolled-over part of the rim is badly designed, it may provide a ledge where product debris can lodge. This soil can indirectly affect the product. (B) Open top rims must be rounded in a way that at one side the product drains back in the bulk of the product, while the more exterior part of the rim must allow drainage to the outside. Where preference is given to closed top rims, the top rim should be welded correctly to the wall over its full length. The weld must be flush and polished to provide a smooth surface. The rim must be totally closed and any holes sealed by welding or by fitting sealed caps (Hauser et al., 2004b).