Ovens

Ovens, also known as drying Ovens, are devices used to dry and sterilize glass and metal containers used in various laboratory processes. The laboratory Ovens allow to carry out the sterilization by dry heat, where hot air is used to carry out this process, these equipments allow a uniform distribution of heat inside, where the material is exposed to temperatures of approximately 170ºC for 2 hours. 

Dry heat sterilization works by destroying microorganisms by oxidation of their cellular components. This is a less efficient process than wet heat sterilization because microorganisms die more quickly when in the presence of water because it allows their protein configuration to be altered more easily and provides a means to distribute heat evenly throughout the sterilizing equipment's internal chamber. For this reason, to achieve the sterilization of the material using dry heat, higher temperatures should be applied for a longer time. 

To sterilize using hot air it is necessary to place the objects in a Ovens. And bring the indoor air to a temperature between 150 and 190 degrees C. The sterilization time must be determined for each type of material, for example, in the case of materials that are quite resistant to heat, higher temperatures can be used for shorter periods of time. 

One of the first equipment used for this purpose was the Pasteur ovens, which was later replaced by hot air Oven. The drying Ovens are composed of a double chamber, and the hot air produced by an electrical resistance circulates through the main cavity and the space between both chambers, at variable temperatures, being the most recommended 170º C for the metal instruments and 140º C for the content of the drums. A stable temperature is maintained through metal thermostats called bimetallic pair, which consist of two metals of different coefficient of expansion. When one dilates, the other does not and arches. One end of this device is in contact with a switch that cuts off the power to the heating resistor.