MATERIAL SOLUTIONS


Pressure


Higher contaminant concentration


Semipermeable membrane


contaminant concentration


Lower


MOLECULAR LEVEL: Reverse osmosis has been used successfully to remove contaminants from cleanroom water, effectively filtering out even large individual bacteria cells at the molecular level


able to withstand upwards of 50 wearing and cleansings, and launderers developed sealed cleanrooms, thing changed. Cleanrooms were constructed and supplied with hepa-filtered air (which was effectively particle-free) and water purified by micro-filtration. By keeping the cleanroom at a slightly positive pressure, sealed and with airlock entry, rental operators achieved basically particle- and fibre-free environments. The fitting of hepa-filters in the cleanroom ceiling enabled downward laminar flow of incoming air, so no turbulence to disturb anything. The extension of inlet water treatment to improve disinfection by UV radiation reduced the risk of bacterial penetration from mains water, which was of particular benefit to pharmaceutical customers. Rental operatives were clad in cleanroom garments themselves (from head to toe, greatly reducing the risk of particle and fibre pick-up from hair, skin and clothing.


Quality assurance can by achieved using a Coulter counter to monitor particle contamination on a continuous basis. Fibre counts can be estimated by the latest counters, but the older method of drawing a known volume of air through a fine graticule and counting the number of fibres in a 25 x 25mm square is still very


@LCNiMag


viable. These techniques enabled the rental operator to meet customer requirements for assured quality with numerical results always available. It also meant that the need for external laboratory measurements was greatly reduced, being used for checking the in-house methods rather than needing to be used for every batch of garments.


Antibacterial garments Garments for wearers in the pharmaceutical industry are frequently required to be not only free from bacteria but also treated with an antibacterial


finish, so that they are resistant to picking up viable bacterial contamination. The historically acceptable method of disinfecting healthcare garments was via implied thermal disinfection, involving a wash process that gave at least 3 minutes (plus mixing time) immersion in water at or above 71C. This has now given way to chemical disinfection, usually in the final rinse of a healthcare wash process. However, achieving antibacterial properties on the garment fabric requires slightly more than chemical disinfection, and modern processes that leave a suitable bacteria resistant finish on the fabric surface involve a substantive residue which bonds to the fibres and yarns. Until recently these finishes would probably have involved a quaternary ammonium compound (a ‘quat’), but there are better, more robust alternatives now available. Again, for the most demanding duties, for which antibacterial performance must be assured, it may be necessary to monitor the number of wear and cleansing cycles and to either re-treat or scrap the garment after a specific number of cycles.


Conclusion


The specialist market for the types of workwear described is a typical example of the premium product which the rental market is capable of providing. It calls for modern quality assurance using some of the newest techniques now available to the rental operator. This makes a refreshing change from customers concentrating purely on the price of the product, to one which takes into account the technical quality of the offering and the technical assurance which goes with this.


LETHAL VIRUS: The advent of a modern, lethal corona virus focused some users of rental garments on the need for sound antibacterial controls


May 2024 | LCNi 29


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