Canadian Packaging

Grace under Pressure

By Davor Djukic   

Optimizing dynamic checkweighing in washdown environments

Microbiological contamination can have devastating consequences for consumers. Aggressive washdown routines using high-pressure rinsing and caustic detergents are the means for risk control in production environments.

The processes are always very similar regardless of operation: rinsing, removing dirt, rinsing the system again; then disinfection to reduce microbiological contamination to a permissible level and rinsing again, provided the disinfectant does not have to remain on the system surface.

Manufacturers often describe systems and equipment that can withstand high pressure wet cleaning and caustic detergents as “washdown-capable.”

However, this designation does not follow a uniform international standardization. It merely reflects the internal risk assessment of the respective manufacturer and sometimes considers industry-specific requirements in the assessment.


The degree of protection of its electrical or mechanical components, the materials used and the system design of the checkweigher from a hygienic point of view must be assessed when evaluating a checkweigher suitable for washdown environments.

The ingress protection (IP) of electrical casings is often of particular interest. An IP66 or IP69 rating usually proves to be sufficient for hygienic washdown environments (IP69 is recommended).

The NEMA rating by the National Electrical Manufacturers Association, which includes a much stronger focus on environmental hazards beyond water and dust—such as NEMA 4 (waterproof casing) and NEMA 4X (waterproof and corrosion-resistant) are recommended for washdown environments, and NEMA 4X for washdown processes in a hygienic production environment, respectively.

Generally, NEMA ratings are best used when combined with an IP rating.

Particular attention must be paid to the extent to which the production facilities in dairies are designed for efficient cleaning processes.

Systems advertised as “washdown-capable” should meet the requirement of making the cleaning process as easy as possible.

For checkweighers in food production, the two standards ANSI 3A 14159-3-2019 and ISO 14159: 2008 are of particular interest. They deal with the design of mechanical conveyor belts for use in meat and poultry production and generally, with the hygiene requirements for the design of machines.

Before making an investment decision, it is also worth looking at the frame construction.

Corrosion resistance and the absence of pores in the materials used are essential. Therefore, the most economical material option is stainless steel. It is smooth, non-porous, non-reactive, non-toxic, and durable.

Customers should pay attention to welds on the frame being smoothed and polished to prevent dirt from building up. Inclined surfaces and rounded frame supports prevent an accumulation of liquids and/or solids in cracks or edges.

Just as much care is required when placing and handling the user interface.

It must be clarified at an early stage whether the user interface can be cleaned in the same way as the rest of the system.

Ideally, the user interface has the same IP rating as the checkweigher. This considerably accelerates and simplifies the cleaning process, as the user interface does not have to be covered or removed.

Production environments in the dairy industry must meet high hygiene requirements to protect consumers from the spread of harmful diseases, bacteria or allergens.

It is worth looking at the small print before making an investment decision, especially with applications such as checkweighing in a washdown environment.

Davor Djukic is national sales manager for product inspection at Mettler Toledo Inc. in Mississauga, Ont.


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