Hot air sterilizer Hot air or oven is a device in use to sterilizing items that moist should not penetrate. That is items that will damage by exposure to moist heat. Such items include powders, sharp instruments and petroleum products etc. In other words, we use dry heat sterilization for articles for which other methods such as using autoclave are not good. At the same time, hot air ovens are in use for articles that can withstand high temperature.
Hot Air Sterilizer Description
Hot Air Sterilizer Principles
The oven produces heat through sets of resistance heating elements, The heat energy is being transferred to the chamber by natural means as well as by forced convection if there is a fan. The heating elements are located in the at the bottom of the oven
In order to use the sterilizer/oven, first activate the main switch, press the button or dial the knob to set the oven temperature and set the sterilizing timer. The inner chamber of the sterilizer will heat up till the oven reach the set temperature. When the sterilizer reached the set temperature, a thermostat activates the timer and the timer begins to countdown until it reach the set time. At this time, it switch off power to the heating elements. However, the elements continues to work via the thermostat control until the set time.
Hot Air Sterilizer Parts and Functions
- Thermostat
- Glass Thermometer
- Heating element
- Timer (sometimes called mechanical run-back timer)
- Neon Indicators
There is a thermostat controlling the temperature. The thermostat automatically regulates and maintains already set temperature. It on or off a device such as an heating element when the temperature reaches a certain set point. Some types are of simple rod thermostat while some are electronic or digital.
Glass thermometer is an instrument for measuring and indicating temperature. Typical one consist of a narrow, hermetically sealed glass tube marked with graduations and having at one end a bulb containing mercury or alcohol. The mercury or alcohol expands and contracts in the tube with heating and cooling. In our context, the thermometer visually indicate the working temperature of the sterilizer.
Basic Hot Air Sterilizer Circuits Diagram
Use of Hot Air Sterilizer
A complete cycle involves heating the oven to the required temperature. Likewise, it maintains that temperature for the proper time interval for ‘that temperature’. Then turning the machine off and cooling the articles in the closed oven till they reach room temperature.
The standard settings for a hot air oven are:
- 1.5 to 2 hours at 160 °C (320 °F)
- 6 to 12 minutes at 190 °C (374 °F)
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