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Enclosure Washdown 101

Tue, 08/07/2007 - 12:40pm
How pharmaceutical manufacturers can help ensure product and operations integrity through proper enclosure washdown procedures

When choosing an enclosure, consider all of its washdown attributes, including – construction and quality, design, hinging, sealing/gasketing, mounting and latching
Cleanliness may indeed equate with godliness, but pharmaceutical manufacturers will need more than divine intervention to ensure that the nooks and crannies of their processing environments are clean and contaminant-free. Maintaining a sanitary environment for hardworking, mission-critical machinery is crucial, and removal of all waste materials and residues from processing systems and controls is essential. Thorough washdowns are a key component in protecting the integrity of manufacturers' products, operations and investments by ensuring cleanliness and preserving product purity and quality.

Incomplete washdowns have detrimental consequences. They can result in an assortment of headaches such as contaminated products, production delays, lost productivity, reduced sales, product recalls, litigation, tarnished company reputations and diminished brand equity. To avoid these unwanted scenarios, manufacturers should eliminate, or minimize to the greatest extent possible, areas in which contaminants can accumulate and make the areas that can't be eliminated easier to access and clean.

Many factors must be taken into account to ensure washdown cleanliness, high quality output and a clean process changeover restart. Among these are the staffs' washdown skill levels, the types of chemical and heat treatments utilized, electrical equipment protection and industry standard compliance.

Equally important but often less considered, and the main topic of this article, are the enclosures used in and the enclosure attributes required for washdown applications. These attributes include enclosure construction and quality, design, hinging, sealing/gasketing, mounting and latching.
Enclosure Attributes
Construction and Quality
An enclosure's construction and quality should be evaluated to determine if the enclosure will withstand harsh chemical washdowns. Enclosures used in such applications need to be made of a non-absorbent material. Type 304 and 316L stainless steel are typically specified. An enclosure's finish is also important, because it facilitates complete washdowns and the removal of contaminants that can accumulate and grow on enclosure surfaces. A #4 finish is recommended.

It's also beneficial to select enclosures that have smooth welds and are produced by a manufacturer that has automated manufacturing processes. This automation helps ensure quality consistency and repeatability so there's minimal product variation from order to order.

If enclosure modifications are required, some manufacturers can ship the enclosures modified as specified, saving the customer time and additional expense. Again, it's important that the manufacturer uses automated manufacturing processes to help ensure the modifications are as ordered, in the correct locations and consistent.

Design
Common enclosure-related problems that reduce washdown effectiveness include washdown solution pooling, contaminant entrapment between walls and wall-mounted enclosures, and unreachable and recessed areas created by free-standing enclosure floor stands. These challenges, which are particularly problematic in and around tightly enclosed control systems and process electronics, can be efficiently and effectively overcome when addressed early in the design process.

For example, incorporating sloped top enclosures into the design can help prevent washdown solution pooling, maximizing system uptime and reducing process changeover downtime. Optional wall-mount enclosure stand-offs facilitate washdown by providing easy access to the back of the enclosure. Difficult-to-clean, free-standing enclosure floor stand areas can be minimized by designing small floor stand or leg footprints. And even the enclosure finish is an important design item since smooth welds and shallow crevices support a hygienic surface that minimizes entrapment.

Hinging
Asymmetrical, lift-off, bullet-style hinges are the best choice for washdown applications. Their rounded top and smooth finish allow complete and easy hinge area cleaning, minimize entrapment and provide easy enclosure access. Piano/continuous hinges, by nature of their design, are not conducive to getting or keeping clean.

Sealing/Gasketing
The importance of using an enclosure that has a properly installed and adhered and high-performing seal or gasket cannot be overstated. Seals/gaskets and their adhesives must be constructed of materials that are compatible with stainless steel. They must also withstand harsh, high-pressure washdowns and be checked periodically for resiliency loss and compression.

Likewise, holes, cut-outs and components must also be completely sealed with materials that meet the aforementioned requirements, and ULType 4X rated connectors should be used on all conduit and/or controls entering the enclosure.

Mounting
As previously mentioned, difficult-to-clean, free-standing enclosure floor stand areas can be minimized by designing small stand or leg footprints. Adjustable legs are also worth considering. They support an enclosure while accommodating the floor's drainage slope without having to be shimmed, reducing potential entrapment areas.

Latching
Standard industrial enclosure latching is generally not suitable for washdown applications. It's typically not designed with features that facilitate washdown runoff and may not have adequate seal integrity.

Because latches can be difficult to keep clean, low-profile, meaning flush with the enclosure, and/or smooth latches with a minimal number of openings, such as slots, are most often specified for washdown applications. And as important as it is to keep contaminants off of and away from the handle, it's equally important that the handle latches forcefully enough to keep washdown solution out of the enclosure.
Additional Non-enclosure Considerations
Proper Washdown Training/Chemicals
It almost goes unsaid that washdown staff training and skill level play a role in ensuring cleanliness, and it's imperative that the staff is educated about their facility's proper washdown techniques and solution composition. Inadequate washdowns can lead to a multitude of problems, and a too rich or weak solution can impact the sanitation level or worse, damage the overall system. And the cleaning doesn't end with the actual washdown; particulates from certain solutions can float and linger in the air for as long as four hours, affecting product purity.

Equipment Protection
While it's obvious that an enclosure must be appropriately rated for its application/environment, it's not so apparent that the components going inside the enclosure must also be rated for that application. If the components have a lower rating than the enclosure, the enclosure will be de-rated to the components' level.
Standards
Several well-known organizations have created washdown environment enclosure performance standards. These standards are chiefly concerned with high water pressure and liquid temperature, since machinery can be quite sensitive to high-pressure spray or hot temperatures.

The National Electrical Manufacturers Association (NEMA), Underwriters Laboratories Inc., (UL) and Canadian Standards Association (CSA) are standard-writing organizations commonly recognized in North America. Their ratings are based on similar application descriptions and expected performance.

UL and CSA require enclosure testing by qualified evaluators. They also send site inspectors to ensure that manufacturers adhere to prescribed manufacturing methods and material specifications. NEMA does not require independent testing and leaves compliance entirely up to the manufacturer.
Summary
Maintaining sanitary pharmaceutical processing environments and protecting the associated control systems from high-pressure and/or high temperature washdown solutions are ongoing challenges. Specifying enclosures that contain the features designed for such applications - high quality and correctly constructed, designed, hinged, sealed, mounted, latched and rated, combined with staff washdown procedure training, can help manufacturers overcome these challenges.
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