CAGE PROCESSING in Animal Facilities - Felasa

WashingHot water mixed with detergent (alkaline, pH neutral, or acid) is sprayed from a tank via jets onto the itemsto be washed. In cage and rack washers the detergent solution (also called detergent liquor) is collected in atank beneath the chamber where it is pumped back into the washing tank. In cabinet and tunnel washers thewater is collected in the washing tank placed underneath, where it is recirculated. Thus, the items can be sprayedwith a high volume flow of water and detergent solution, making additional fresh water unnecessary duringthe washing phase.Where required, it is possible to perform a series of washings, with for example alkaline and acid detergents.Therefore the washer must be equipped with several washing-tanks. Usually, the washing water solution is largelyrecirculated for the following loads to reduce the water consumption as much as possible. Approximately4 - 7 percent of water is newly added.To reduce the amount of water needed to rinse off the items, it might be helpful in cabinet washers and cageand rack washers to wait for the detergent solution to drip off first.NeutralisingTo ensure there are no residues left, an item washed with alkaline detergents requires neutralisation. This canbe achieved either by an immediate neutralisation step prior to the rinsing process or trough using an acidrinse aid for the rinsing process. Neutralising is particularly important for polycarbonate (PC) cages in order toprevent the material from being damaged by alkaline residues in the steam sterilisation process.RinsingResidual detergent is removed with clear hot water that is sprayed via jets on the washer load. A rinse aid(also acid rinser for neutralisation) can be added. To avoid lime scale or salt deposits it is recommended touse demineralised water. Polysulfone (PSU) requires material-specific rinse aids.Detergent solution should not be mixed with rinsing water.DryingThe purpose of the drying process is to dry the items to an acceptable residual moisture.With suitable rinse aids, added during the rinsing process, the items can dry faster after being removed fromthe chamber.In tunnel washers, the items are usually dried in a drying zone with hot air. This is a continuous process. Theresulting vapours should be exhausted through integrated extraction hoods at the entry and exit area of thetunnel as well as in the rinsing zone. This central exhaust process can be combined with a heat recovery.With cage and rack washers, hot-air can be used for the drying process. The aeration of the chamber removesthe residual moisture from the load. In wash cycle-type machines, the drying can further be enhanced by feedingclean steam into the chamber.For bottle washers, added rinse aid or a subsequent hot-air drying is not necessary, as, usually after washing,water bottles are refilled with drinking water.UnloadingUnloading in case of cabinet, rack, and bottle washers means that the loading trolleys or racks are removedfrom the chamber and cleared of the items. In case of tunnel washers (or if applicable of semi- or fully automaticbottle washer), of course, the belt is cleared. While unloading, a final drying outside the machine begins.Final drying outside the machineStored heat in the washed items helps potential residual moisture to evaporate (drying by specific heat). Thisrequires a sufficient heating of the items while being rinsed or dried inside the machine. Where necessary, provisionsshould be made to prevent the operating staff from getting burnt by the specific material heat (e.g. settingup a final drying zone with warning notices; defining a minimum cooling time for a safe handling of items).Cage Processing in Animal Facilities · 4th issue · 2013 21