Hot air ovens are electrical devices which use dry heat to sterilize. They were originally developed by Louis Pasteur.[1] 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. There is also an air filled space in between to aid insulation. An air circulating fan helps in uniform distribution of the heat. These are fitted with the adjustable wire mesh plated trays or aluminium trays and may have an on/off rocker switch, as well as indicators and controls for temperature and holding time. The capacities of these ovens vary. Power supply needs vary from country to country, depending on the voltage and frequency (hertz) used. Temperature sensitive tapes or biological indicators using bacterial spores can be used as controls, to test for the efficacy of the device during use.
They do not require water and there is not much pressure build up within the oven, unlike an autoclave, making them safer to work with. This also makes them more suitable to be used in a laboratory environment. They are much smaller than autoclaves but can still be as effective. They can be more rapid than an autoclave and higher temperatures can be reached compared to other means. As they use dry heat instead of moist heat, some pathogens like prions, may not be killed by them every time, based on the principle of thermal inactivation by oxidation.[citation needed]
Usageedit
A complete cycle involves heating the oven to the required temperature, maintaining that temperature for the proper time interval for that temperature, 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)
....plus the time required to preheat the chamber before beginning the sterilization cycle. If the door is opened before time, heat escapes and the process becomes incomplete. Thus the cycle must be properly repeated all over.
These are widely used to sterilize articles that can withstand high temperatures and not get burnt, like glassware and powders. Linen gets burnt and surgical sharps lose their sharpness.
Referencesedit
^Ananthanarayan, R; Paniker, C. J. (2006). Textbook of Microbiology (7th ed.). India: Orient Blackswan. pp. 2, 25–26. ISBN978-8125028086.
oven, consumer, device, heat, food, convection, oven, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspape. For the consumer device to heat food see Convection oven This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Hot air oven news newspapers books scholar JSTOR June 2019 Learn how and when to remove this template message Hot air ovens are electrical devices which use dry heat to sterilize They were originally developed by Louis Pasteur 1 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 There is also an air filled space in between to aid insulation An air circulating fan helps in uniform distribution of the heat These are fitted with the adjustable wire mesh plated trays or aluminium trays and may have an on off rocker switch as well as indicators and controls for temperature and holding time The capacities of these ovens vary Power supply needs vary from country to country depending on the voltage and frequency hertz used Temperature sensitive tapes or biological indicators using bacterial spores can be used as controls to test for the efficacy of the device during use Hot air oven Contents 1 Advantages and disadvantages 2 Usage 3 References 4 External linksAdvantages and disadvantages editThey do not require water and there is not much pressure build up within the oven unlike an autoclave making them safer to work with This also makes them more suitable to be used in a laboratory environment They are much smaller than autoclaves but can still be as effective They can be more rapid than an autoclave and higher temperatures can be reached compared to other means As they use dry heat instead of moist heat some pathogens like prions may not be killed by them every time based on the principle of thermal inactivation by oxidation citation needed Usage editA complete cycle involves heating the oven to the required temperature maintaining that temperature for the proper time interval for that temperature 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 plus the time required to preheat the chamber before beginning the sterilization cycle If the door is opened before time heat escapes and the process becomes incomplete Thus the cycle must be properly repeated all over These are widely used to sterilize articles that can withstand high temperatures and not get burnt like glassware and powders Linen gets burnt and surgical sharps lose their sharpness References edit Ananthanarayan R Paniker C J 2006 Textbook of Microbiology 7th ed India Orient Blackswan pp 2 25 26 ISBN 978 8125028086 Textbook of Microbiology by Prof C P Baveja ISBN 81 7855 266 3 Textbook of Microbiology by Ananthanarayan and Panikar ISBN 81 250 2808 0External links edithttp www tpub com content medical 14274 css 14274 146 htm Retrieved from https en wikipedia org w index php title Hot air oven amp oldid 1218058450, wikipedia, wiki, book, books, library,
