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Protect Sensitive Electrical Controls While Maximizing Sanitary Conditions

Tue, 11/18/2008 - 10:02am

Stainless steel electrical enclosures and cable management systems such as cable tray are used to protect vital processing controls, electrical systems, and data and power cabling in pharmaceutical applications. Yet while these enclosures and cable tray fittings perform the critical task of protecting sensitive electrical componentry, they can contribute to dangerous and costly product contamination events if not properly designed and rated to meet industry requirements. To maintain stringent sanitary conditions, enclosures and cable tray fittings should feature sloped tops and covers, smooth, flush surfaces, minimal ridges and other potential bacteria catch points as well as mounting and design options that facilitate cleaning and effectively minimize the impact of shut downs. Many of these design criteria are specified by standards originally intended for the food & beverage industry. For example, NSF International, an independent, not-for-profit, non-governmental organization, developed a set of standards—the NSF/ANSI 169—that specifies the essential design criteria for food equipment and devices, such as electrical enclosures.

Enclosure Application Overview


The most common enclosure and cable management applications in the pharmaceutical industry are for protecting variable frequency drives (VFDs), programmable logic controllers (PLCs) and power and data cabling, all of which together power and control machinery designed to produce and package pharmaceutical products. For example, enclosures often contain the robotic control components utilized in pharmaceutical applications—from drug discovery to production and packaging. These enclosures are either isolated from the manufacturing processes or within their proximity to enable localized control and maintenance. Additionally, cable management systems such as stainless steel cable tray are needed to distribute power and data for these processes.

Enclosures used in close proximity to manufacturing areas


Applications that call for controls and related electrical components to be placed in close proximity to manufacturing and packaging processes are on the rise. One example is the increasing use of robotics on the packaging line. Advances in technology allow more efficient picking, packaging and palletizing robotics that deliver accurate, high-speed operation to increase overall productivity. For example, robots can pick vials that are on a moving conveyor, put them in the correct orientation and stack them in a specified quantity. The vials are then placed into packaging wells and wrapped with a material such as aluminum foil. The controls for these robots and other automated applications are housed in enclosures, which must meet certain sanitary design standards since they are located in close proximity to the manufacturing process. Features to consider when selecting an enclosure for these sanitary applications include sloped surfaces and door flanges, beveled door edges, removable bullet hinges, smooth and rounded mounting feet and stand-off kits—all of which work to minimize areas where dust, debris and pharmaceutical product can accumulate and promote bacteria growth or product contamination.

Smooth, bullet-style hinges are ideal for pharmaceutical applications. These hinges allow easy access to the enclosure, with minimal places for contaminant entrapment. Plus, bullet-style hinges can be easily lifted off—without the use of tools—for easy cleaning inside and out, and door edge cutout provisions make flushing with sanitizing solutions possible.

Seals and gaskets—which are necessary for an enclosure to successfully protect enclosed components—must also meet certain requirements. Continuous foam-in-place gaskets eliminate seams and offer consistent resilience to wipe-down, and all seals, gaskets and adhesives must be compatible with stainless steel and be regularly checked against resiliency loss and compression.

Another potential threat to sanitary conditions comes from moisture that can accumulate as a result of condensation and the chemicals sprayed for sanitary purposes during wipedown. Enclosures with a sloped top protect against moisture-related damage by promoting runoff away from process equipment, maximizing sanitation and minimizing downtime needed for cleaning and maintenance. Sloped door flange trough collars and sloped door edges also aid in directing runoff away from an enclosure and its components.

Selecting a material with a high degree of corrosion resistance also protects against moisture related damage. While enclosures are available in a wide variety of material options—including non-metallics and metallics—not all materials offer the same level of defense. Stainless steel—known for its superior resistance to corrosion—provides various degrees of protection, according to its chemical composition. Type 304 stainless steel (18-8) was named to reflect its 18% chromium and 8% nickel composition. Type 316 stainless steel, a higher-grade version, has a 10% nickel, 16% chromium and 2% molybdenum content. While nickel and molybdenum provide increased corrosion resistance to chlorides and many common industrial chemicals, chromium delivers a protective surface film.

An increasingly important factor that impacts enclosure selection for pharmaceutical industries is aesthetics. Stainless steel enclosures with minimal rough surfaces can enhance the overall hygienic appearance of pharmaceutical processing industries and can be chosen to blend in with surroundings or feature a variety of design options.

Enclosures used for pharmaceutical applications should be mounted so contaminant entrapment—between a wall and a wall-mount enclosure or in unreachable, recessed areas created by floor stands and free-stand enclosures—is minimal. Sanitary stainless steel standoff kits minimize contaminant entrapment between wall and wall-mounted enclosures, while allowing the opportunity to fully wipe-down all surfaces behind the enclosure. For free-stand enclosures, tapered stainless steel sanitary leg kits are key. These kits minimize floor contact and raise enclosures to facilitate wipe-down access underneath the enclosure.

Clean room enclosure requirements


For applications that call for controls or other electrical components to be mounted directly in the area where pharmaceutical products are manufactured, additional design, mounting and enclosure finish options should be considered.

Flush mounting an enclosure—that doesn't protrude into the manufacturing area—into the wall of a clean room eliminates potential for build-up of bacteria and other undesirable debris while economizing on available space. Additionally, continuously welded seams that are grounded smooth prevent this accumulation and bacteria growth. An enclosure utilized in a clean room should also feature a finish with a low RA value, which minimizes surface crevices, allowing for a more thorough wipe-down.

Gaskets on clean room enclosures should include additional sanitary design criteria. This is because bacteria growth on gaskets can appear invisible, remaining undetected by workers. FDA-approved white gaskets, however, will trigger an action to clean the area as needed.

Powering controls and protecting cables


Due to the increase of robotics use, proper cable management has also garnered extra attention as a result of increased need for power and data transmission. Cables bring power and data to and from the controls for these robots and their motors, and systems used for cable management must be rated for the environment where they are located.

Modular stainless steel cable tray systems designed for rated cable offer a complete range of sections, fittings and accessories, allowing simple installation of custom runs. Sloped-cable tray systems are particularly pertinent to the pharmaceutical industry, as it is possible to mount cable tray runs flush against walls or machinery to minimize the risk of product entrapment and potential contamination. In addition, stainless steel cable trays provide corrosion resistance while maintaining a clean aesthetic.

Smooth surfaces, proper mounting and corrosion-resistant material allow enclosures and cable management systems to protect electrical and electronic controls and cables, while maintaining a sanitary environment required by a broad range of pharmaceutical applications.
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