Hot Air oven

The hot air oven was originally invented by Pasteur. It works on the principle of dry heat to sterilize the products which are used in various industries. The device is ideal for the heat operation ranging from 50 degrees to 300 degrees Celsius.

Generally, they use a thermostat to control the temperature. Their double walled insulation keeps the heat in and conserves energy, the inner layer being a poor conductor and outer layer being metallic.

Sterilizing by dry heat is accomplished by conduction. The heat is absorbed by the outside surface of the item, then passes towards the centre of the item, layer by layer. The entire item will eventually reach the temperature required for sterilization to take place.

Glassware such as bottles, petri dishes and test tubes are sterilized by using dry heat in a hot air oven. The ideal temperature of the oven needs to reach is at least 160°C  for 45 to 60 minutes.

Sterilization involving lower temperature and high-pressure of water (steam) is known as Moist Heat Sterilization.

Autoclaving and Boiling come under moist heat sterilization. Incerination, Bunsen burner (flame), hot air oven and microwave comes under dry heat sterilization.