Design Guidelines of Electronic Enclosures for Hygienic Environments

sponsored by

Introduction

Food & Beverage (F&B) industry maintenance personnel have long been compelled to perform extra, time-consuming actions to shield critical electrical and electronic equipment prior to equipment cleaning or washdowns. Not doing so could result in unwelcome production delays and product safety losses, due to water ingress and bacteria-nurturing catch spots. An enclosure produces a safe environment for vulnerable electrical components from the environment. Enclosures purpose-built to satisfy F&B production lines in sanitary environments are generally termed "Hygienic Design" enclosures. This article provides an overview of the current and relevant directives, regulations, and guidelines, and focuses on the difficulties encountered by the F&B industry. It also delves into hygienic design principles and their applications.

Defining Hygienic Design

The essence of hygienic design is protecting electronics used in automation and control, while also preventing food contamination, corrosion, the ingress of harsh cleaning products, and other factors in a wash-down environment. It is crucial to eliminate undercuts or 'dead spaces,' as these points are predisposed to product residue accretion, which constitutes a perfect substrate for microbial corruption. The use of chemicals, such as chlorine bleach, to achieve a sterilized food processing ecosystem may degrade improperly protected electrical panels. Also, washdowns are accomplished using high-pressure hoses spewing chemical or water solutions.

In 2018, the U.S. Centers for Disease Control and Prevention (CDC) investigated more than 20 multistate foodborne disease outbreaks—more than any previously recorded year—and more than 200 food recalls. As a result, it became imperative that F&B manufacturers deploy advanced sanitary solutions inside food processing plants. Electrical enclosures in a processing plant protect the housed equipment and offer safety to everyone in the vicinity. The Hazard Analysis Critical Control Points (HACCP) quality system dictates all official guidelines, regulations, and directives on hygienic design.

Meeting Hygienic Equipment Design Principles

Traditional enclosures fail when exposed to the vagaries of standard sanitary washdown cleaning methods employed in processing plants. In their attempt to prevent these probable failures, maintenance personnel frequently end up taking additional manual steps, such as caulking seals and doors and bagging enclosures to stop moisture from entering the chamber, breeding bacteria and impairing equipment. F&B manufacturers have thus adopted advanced hygienic electrical enclosure solutions. These newly invented, specially designed enclosures can tolerate high-pressure and high-temperature sprays used in sanitary washdown procedures, especially for harsh and clean-in-place applications. Hygienic hardware design principles encompass:

• Surfaces – Almost all standards need a surface finish with a roughness average (Ra) of 0.8 µm (32 µ in) or less.
• Materials – Items should be application compatible, including cleaning processes and chemicals, as well as the food being produced.
• Construction – All food equipment must have self-draining surfaces, with zero crevices or undercuts where soil may gather.
• Installation – The equipment must permit complete access during cleaning. If wall-mounted, it should be offset from the wall or sealed to minimize soil accumulation.
• Maintenance – Items must be designed to endure the severity of high temperature and high-pressure cleaning operations.

Standards for Hygienic Design Enclosures

Hygienic enclosure solutions comply with harmonized global standards that indicate how effective they are in liquid ingress protection (IP), withstanding pressure and temperature ranges, and resisting corrosion. IP69 ratings indicate the enclosure protection level against the ingress of liquids (IPX9) and dust (IP6X). The IP69 (IEC) for electrical equipment and the IP69K (DIN) standard represent peak protection. The 3-A Sanitary Standards constitute hygienic equipment design. The NSF, an international certification body, standardizes U.S. sanitation and food safety requirements. This independent third-party tests and also certifies products to verify whether they satisfy public health and safety standards. The Type 4X certification indicates protection for personnel against access to hazardous parts, as well as superior protection levels for enclosure-contained equipment against the entry of solid foreign objects (such as dust) or water ingress, which may damage vital equipment inside the chamber and foment bacterial growth.

Selecting the Right Product for Hygienic Design

Enclosures must be purpose-built for the demanding conditions connected in the F&B industry. A typical stainless steel electrical enclosure with a 0.8 µm or less roughness average surface finish is acceptable for washdown environments. It satisfies industry standards for liquid ingress prevention and corrosion resistance. Door seals must be low maintenance and easily replaceable. The enclosure should be adequately tough to handle high pressures and elevated temperatures associated with cleaning operations. It must be operationally reliable after multiple cleaning cycles. Other than these fundamental requirements, it is vital to match the right level of protection to the processing application rigor needed to satisfy various industry standards, including UL Type 4X, NSF, IP66, and IP69 ratings.

Application Information of Enclosures for Hygienic Environment

As per standards, an F&B company can be classified into three distinct hygiene categories:

High-level protection: This level is applicable for all surfaces that are in direct contact with food. It also includes paths from which the food returns to the product stream via drainage, dripping, outflow, or leakage. The nVent HOFFMAN HyShed is a total sanitary washdown enclosure solution. It helps protect equipment in clean-in-place and harsh sanitary washdown applications. The product is suited for on-machine controls and areas with considerable temperature swings. The HyShed Screw Cover enclosure maximizes back panel space and features a 10-degree sloped top to stop particulates or fluids pooling. The easily replaceable FDA-grade silicone gasket inhibits bacteria growth and chemical absorption, while simplifying maintenance.  A streamlined hygienic design helps eliminate bacteria-harboring catch points. The entire HyShed portfolio satisfies the industry's highest standards for high pressure, high-temperature cleaning procedures, including IP69K (DIN), IP69 (IEC), NSF, and Type 4X.

Figure 1: HyShed Screw Cover EnclosuresHyShed Screw Cover Enclosures

Medium Level Protection: This level is best for food processing applications where enclosures endure light contact with water spray and chemicals. Ideally suited for food processing areas, these enclosures feature a sloped top, sloped door edges, bullet-style hinges, and shield electrical equipment in sanitary washdown applications. The product is specially designed to facilitate washdown runoff. The WaterShed portfolio features 22 wall-mount, seven free-stand, and 14 disconnect models. It features corrosion resistance with 304 stainless steel construction, a stainless steel quarter-turn latch, and insert-on wall-mount enclosures, along with stainless steel HOFFMAN Power Glide handle on free-stand enclosures. Suitable sloped top enclosures meet IP66, Type 4X, and NSF standards.

Figure 2: WaterShed Stainless Steel Free-Standing EnclosuresWaterShed Stainless Steel Free-Standing Enclosures

Basic Level Protection: This level is for applications with zero food contact, requiring minimal washdown or chemical contact. The sloped top enclosures satisfy IP66 and Type 4X standards.

Figure 3: Concept Sloped-Top EnclosuresConcept Sloped-Top Enclosures

The nVent HOFFMAN Company also introduced a few accessories available for hygienic enclosures, including the IP69K Stand-Off Kit, Replacement Blue FDA-Grade Silicone Gasket, Sanitary Stand-Off Kit, Sanitary Leg Kit, Replacement Silicone Strip Gasket, Padlocking Latch Kit, Padlocking Handle Kit, and Corrosion Inhibitors.

Conclusion

By applying the correct level of electrical enclosure solution protection to washdown applications, F&B manufacturers will minimize bacterial growth and other contaminants risk, resist equipment corrosion, and promote longer lifecycles for control drives. The proper protection will also simplify routine maintenance for sanitary washdown procedures.