Monday, 11 January 2021

Ingress Protection and Durability: Two of the Most Important Features of Cleanroom HMI Workstations


 In my earlier posts on Pharmaceutical Microbiology, I laid out some of the benefits of mobile human–machine interface (HMI) workstations in the pharmaceutical industry. Specifically, I highlighted their ergonomics, cleanability, and overall cost-effectiveness, as well as how they enhance various cleanroom practices. In this final article, I’ll do a deep dive into two of their more important features in a cleanroom context: ingress protection and durability.

A guest post by Jason Maurer (onlinestrategen.dk/Blue Line)

Ingress Protection

            Ingress protection (IP) is a term often used in manufacturing contexts that refers to the degree to which a piece of equipment is sealed from external substances, particularly liquids and dust. In the case of HMIs, this means the extent to which their delicate insides are protected from moisture and dust. The IP rating, which is given at manufacture, is a combination of two numbers (e.g., IP65) that determine the extent to which the device is secured from contaminants. The first number, which describes the degree of protection from solids, ranges from 0 to 6, while the second, which describes protection from liquids, ranges from 0 to 8 (there is also a separate 9K liquid rating, but this is irrelevant to a pharmaceutical context). For instance, an IP65 monitor is fully protected from dust and can be sprayed with low-pressure water. The IP rating has long been an international standard, alongside standards like the NEMA. 

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            In pharmaceutical cleanrooms, delicate equipment such as lighting and monitors require relatively high IP ratings because anything less risks not only a short unit lifecycle due to the rigorous cleaning practices employed therein, but also because it risks introducing contaminants. Because pharmaceutical cleaning procedures typically involve spraying liquids onto the screens and surfaces for wiping downs and wet vacuuming, they typically require an IP65 rating, which is achieved through a combination of sleek design (minimal edges and cavities in which liquids and bacteria can hide—see Figure 1) and a pressurized interior (not unlike that used to ensure the integrity of the cleanroom) sealed via gaskets. Fanless cooling also ensures greater longevity and further protection against contamination, as it prevents the buildup of heat, which not only leads to the deterioration of the electronics but also can interact with moisture and particulates to increase bacterial growth.

 



Figure 1. Monitors with smooth, rounded edges offer few spaces for moisture and bacteria to hide and allow for easy wiping


            Although there are higher IP ratings than IP65 (e.g., IP68 or IP69K), they are typically unnecessary for cleanroom environments. For example, IP68 allows the unit to be completely submerged in water for a period of time, while IP69K allows for high-temperature jet washing, which is typically only necessary in food processing. Neither are worth the added cost in cleanrooms, where regular cleaning is typically more localized and efficient.

 

Durability

            Besides IP, the durability of cleanroom HMIs and computers—in particular, the degree to which they can withstand repeated exposure to powerful acids and chemicals—is an exceedingly important feature. This feature compounds with IP to ensure a long-lasting, cost-effective piece of equipment that can be used daily in multiple usage cases.

            In class B and C cleanrooms, HMI workstations are typically built of AISI 316L stainless steel. This alloy is known for its low carbon content (the “L” stands for “low carbon”), which helps in protecting against corrosion. Accordingly, the entire unit can be exposed to highly acidic and corrosive substances (often used in cleaning) without worrying that the materials will degrade. This means that common cleaning agents—isopropyl alcohol, non-deionized water, Spor-Klenz™, vaporized hydrogen peroxide (VHP), Klercide™, Actisan, LpH®, and Vesphene®, to name a few—will not affect the unit at all, even after prolonged exposure. Some HMI manufacturers, like Blue Line, make sure of this through making use of the SEFA 24-hour test (1). This involves exposing the materials of the device to a given contaminant for 24 hours and observing its effects. An “excellent” is achieved if there is little to no change in the material after 24 hours. Ideally, HMIs should achieve “excellent” ratings for all common contaminants.

 

Conclusion

            IP ratings and durability are both necessary factors to consider when choosing equipment for cleanrooms. Rather than always opting for the highest levels of protection, however, it is important to ensure that you consider the specific usage cases for the computers, including to what extent it will be moved, how often it will be used, and the class of cleanroom. That way, you get more value.

 

References

(1)   https://www.sefalabs.com/about-sefa

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