Steam sterilization achieves by exposing the items to sterilizing with saturated steam under pressure. Heat enhances the ability of heat to kill microorganisms by reducing the time and temperature required to denature or coagulate proteins in the microorganisms.
A basic principle is Gay Loussac’s law when the pressure of a gas increases the temperature increase proportionally. With about 15 pounds of pressure per square inch (psi), the temperature rises to 121oC. Increasing the pressure to 20 psi raises the temperature to 134oC.
An electric steam sterilizer uses steam to kill any germs. The sterilizer unit sits on your bench top and is plugged into the power socket like a toaster or electric kettle. You pour a small amount of water into the unit, put the cover on and the metal element at the bottom heats up, turning the water to steam.
- Steam flows through the sterilizer beginning the process of displacing the air.
- Exhaust valve will close, causing the interior temperature and pressure to ramp up to the desired setpoint.
- Desired temperature maintain until the desired time is reached.
- The pressure release from the chamber through an exhaust valve.
a. Chamber and jacket.
b. Thermostatic traps.
c. Vacuum system.
d. Steam generator.
The chamber is the primary component of a steam sterilizer where the materials to be sterilized are placed and sterilization happens & the jacket is filled with steam, reducing the time that sterilization cycles take to complete and reducing condensation within the chamber.
A device designed to allow air and water (condensate) to escape from the chamber. Steam traps are temperature sensitive valves that close when heated past a set point.
Forcibly remove air by pulling a vacuum on the chamber before the cycle (also known as pre-vacuum), it also helps by pulling a vacuum after the cycle (also known as a post- vacuum) to remove the steam remaining in the chamber and dry off the goods inside the autoclave.
Boilers are typical underneath the chamber to the sterilizer and utilize electric heating elements to heat water and generate steam.
5 Phases of Sterilization
1. Phase conditioning
a. Chamber closes with jacket.
b. Steam loaded.
c. Jacket pressure and chamber pressure displayed.
2. Heating conditioning
• Steam generated
3. Sterilization phase
• 121 C at 10 psi in 20 min
• 134 C at 20 psi in 5 min
4. Dry phase
• Removal of water
• Releasing high pressure
• Use vacuum