Pharmaceutical manufacturers, high-tech companies and food producers: They all manufacture goods that must not come into contact with dirt particles - but such particles are present in abundance in normal air. In the city, for example, one cubic metre of air contains around 500,000 particles. Sensitive products are therefore manufactured in cleanrooms in which the number of particles is reduced to a minimum. So far, so clean. But what about the employees' clothes? After all, particles may also stick to the clothes and then contaminate the cleanroom. A remedy is provided by the first cleanroom laundry in Germany, which CWS-boco opened in Heidenheim in early September - following locations in Ireland, Belgium and Poland. "It is mainly human particles such as flakes of skin and hairs that need to be washed out of the clothes," explains Werner Münnich, cleanroom expert at CWS-boco. To this end, the company has integrated a cleanroom in the existing operating hall - the above-mentioned cube, which contains a maximum of 352 particles per cubic metre of air.
Air, water, heat - everything clean
The cleanroom cube is located at the back of an industrial washing machine. This machine is loaded from the front, under normal conditions still. But as soon as the employee has closed the door of the drum, the air inside it is replaced by filtered air from the cleanroom. The load is washed with reverse osmosis water, which is almost completely pure and lime-free. CWS-boco uses steam to warm up the water - but its heat is transferred only indirectly since otherwise the air would become contaminated again. Capacity utilisation in the cleanroom is also different: "The machine can be loaded with 80 kilograms, but for clean washes a maximum of 70% of this capacity is used," explains Jan Ulrich, who has overseen the cleanroom project right from the start. "The ratio of water to textiles is important as we need enough water to really wash all bacteria and particles out of the clothes."
Once the machine is finished, employees unload the clean laundry on the other side in the cleanroom and place it in the dryer. Huge air-filter boxes ensure that the air here is also free of particles. Still in the cleanroom, the employees fold up the clothes. Before the textiles can leave the cleanroom, they are heat-sealed by a machine while on the conveyor belt: Now, contaminated air can no longer get to the washing.
Wet or dry?
One striking feature in the cleanroom is the red and blue trays for transporting the clothes. "The colours help the employees tell whether laundry is wet or dry. This is something they can't feel through two pairs of gloves," says Ulrich. Because of course, it is not enough to wash the textiles free of particles: The employees have to go through a strict programme before they even enter the cleanroom. They have to pass through three airlocks before they have finished putting on their cleanroom uniform: polyester trousers and jumper, bouffant cap, clogs, overalls, face mask, hood, overboots, protective goggles, two pairs of gloves - while repeatedly washing and disinfecting their hands in between. Only when they reach the final airlock can the employees stop a while to catch their breath: An air current here ensures that the last particles also settle on the ground. It is not just because of their outfits that the employees resemble astronauts now - their motions are also similar: To avoid stirring up particles to the greatest extent possible, they move very slowly.
Computers have to stay outside
Pallet cages, folding tables and transport trays also are not allowed into the cleanroom without being treated: First, they have to go into the autoclave. This large steam steriliser reaches a temperature of 134 degrees Celsius and can rid up to a hundred objects of microorganisms in an hour. However, computers and other technical equipment cannot withstand this treatment, and moreover these devices have fans that stir up particles again - so in the cleanroom they are taboo. "We therefore moved all technical equipment outside and only laid cables that lead inside," explains Ulrich. This also saves space, which is already in short supply in the cleanroom: No more than five employees can be there at a time, otherwise it gets too crowded and there is also not enough air for more. The team currently deals with 1,200 items per shift, but this is not the end of the road. "We deliberately decided on a modular structure so that we can expand the cleanroom laundry if there is enough demand," explains Detlef Kröpelin, Chairman of the Management Board of CWS-boco Germany. The prospects are good, as the German economy is becoming increasingly specialised, which also results in a growing number of cleanrooms for which suitable professional clothing is then needed. So it is a growing business - in which the price is not the only factor with which CWS-boco can impress customers, as Kröpelin emphasises: "Cleanroom business is based on trust. The customers must be able to rely on the professional clothing meeting cleanroom standards again after it is washed. And we give them this certainty."