Sterilization Autoclave

Equipment that sterilises materials with pressurised saturated steam, combining controlled temperature, pressure and exposure time.

The autoclave makes use of the fact that moist heat destroys microorganisms, including bacterial spores, faster than dry heat at the same temperature: the steam gives up its heat as it condenses on the load and denatures microbial proteins. By increasing the pressure inside the chamber, water boils above 100 ºC; the most common cycles run at 121 ºC or 134 ºC, and the exposure time depends on the temperature and the type of load. For the cycle to work, air must be removed from the chamber and the packs, either by gravity displacement or by pre-vacuum, because air pockets prevent the steam from reaching every surface.

It is used for surgical and dental instruments, laboratory material, culture media and biological waste that must be decontaminated before disposal. It is not suitable for materials that do not tolerate heat or moisture, such as many plastics and electronics, nor for oils and powders, which steam cannot penetrate. The material must arrive clean and dry: organic soil protects microorganisms and hinders sterilisation, so prior cleaning is part of the process.

Steam sterilisation of medical devices is validated and controlled according to ISO 17665, and small sterilisers are governed by EN 13060. The effectiveness of each cycle is checked with physical indicators (temperature, pressure and time records), chemical indicators, which change colour when the cycle conditions are reached, and biological indicators, with highly heat-resistant bacterial spores.