A hot air oven is used to sterilize equipment and materials used in the medical field. This lesson will discuss what a hot air oven is and how it works.
What Is a Hot Air Oven?
Gina is a new employee at South Hospital. She’s working in the sterilization department, which she has little experience in.
Gina’s manager is orienting her to the process of dry heat sterilization using the hot air oven. She begins by reviewing what it is and why it’s used.A hot air oven is a type of dry heat sterilization. Dry heat sterilization is used on equipment that cannot be wet and on material that will not melt, catch fire, or change form when exposed to high temperatures. Moist heat sterilization uses water to boil items or steam them to sterilize and doesn’t take as long as dry heat sterilization. Examples of items that aren’t sterilized in a hot air oven are surgical dressings, rubber items, or plastic material.Items that are sterilized in a hot air oven include:
- Glassware (like petri dishes, flasks, pipettes, and test tubes)
- Powders (like starch, zinc oxide, and sulfadiazine)
- Materials that contain oils
- Metal equipment (like scalpels, scissors, and blades)
Hot air ovens use extremely high temperatures over several hours to destroy microorganisms and bacterial spores.
The ovens use conduction to sterilize items by heating the outside surfaces of the item, which then absorbs the heat and moves it towards the center of the item.The commonly-used temperatures and time that hot air ovens need to sterilize materials is 170 degrees Celsius for 30 minutes, 160 degrees Celsius for 60 minutes, and 150 degrees Celsius for 150 minutes.Gina understands that hot air ovens sterilize equipment over long periods of time, so she has to be organized in determining what items will be sterilized at what time. This depends on when the equipment needs to be available again.
Gina’s manager now explains the different types of hot air ovens.
Types of Hot Air Ovens
There are two types of hot air ovens. One is a forced air hot air oven and the other is a static air hot air oven. The forced air hot air oven is more effective than the static air hot air oven.The forced air hot air oven works by heating the oven and using a fan to move the hot air around. This helps prevent the hot air from rising to the top of the oven and keeping the cooler air at the bottom. The fan keeps the hot air moving around at a consistent temperature throughout the oven.
The static air hot air oven works by using a heating coil at the bottom of the oven. The heat rises throughout the oven and takes a longer time to reach the desired temperature. Since the heat is not circulated as with a forced air hot air oven the temperature is not consistent throughout the oven.
Gina learns that the hospital has gotten rid of all their static air hot air ovens and now only uses forced air hot air ovens. Her manager explains how the oven works.
Functions of Hot Air Ovens
Hot air ovens are large steel boxes that are double insulated. The temperature is digitally controlled and the inside of the ovens are aluminum or stainless steel.
They are easy to install and maintain because they are welded together and painted with epoxy polyester to keep any heat from escaping. The double layers of the oven are insulated with glass fibers of asbestos, and wire mesh or aluminum shelves are adjustable to help fit necessary equipment. The heating elements are on the bottom of the oven, and the fan helps circulate the heat to keep an even temperature with a forced air hot air oven. A thermostat is set up to show the internal temperature of the oven. The items are placed in the oven and it’s then turned on.
The oven works based on the temperature and how long it needs to run to sterilize items. Items need to be cooled down to at least 40 degrees Celsius before they’re removed from the oven.Gina’s manager explains that since the hot air oven sterilization process takes such a long time, ovens are usually run at the end of each day.
This way the equipment will be available for use on the following day. In certain circumstances, the hot air oven is used during the day if equipment is needed a second time later in the day.
Hot air ovens are a type of dry heat sterilization. Dry heat is used to sterilize materials that can’t get wet. Examples of materials that are sterilized in a hot air oven are glassware, powders, items that contain oil, and metal equipment.
Hot air ovens work using conduction to heat the surface of the equipment and absorbing the heat towards the center. Two types of hot air ovens are forced air hot air ovens and static air hot air ovens. Forced air hot air ovens are preferred because they circulate the heat throughout the oven with a fan to maintain a constant temperature throughout the oven. Static air hot air ovens, on the other hand, use a heating coil at the bottom of the oven. Sterilization times depend upon the set temperature and how long an oven needs to run.Medical Disclaimer: The information on this site is for your information only and is not a substitute for professional medical advice.