Dry-heat sterilizers are classified into two types: static-air sterilizers and forced-air sterilizers. Because heating coils at the bottom of the machine allow hot air to rise within the chamber by gravity convection, the static-air sterilizer is also known as an oven-type sterilizer. The force of air flowing over the heating element creates enough pressure within the chamber to ensure that all organisms within the container are killed at the desired temperature for a given time.
The second type of dry-heat sterilizer is the forced-air sterilizer. Here, a fan or blower forces air through metal fins attached to the outside of the chamber. This method of heat transfer allows for faster heat distribution throughout the room than with a gravitational system. Forced-air sterilizers are more efficient than static-air sterilizers and can heat larger amounts of material in a shorter amount of time.
Both types of dry-heat sterilizers use radiation from the sun or electric current to destroy pathogens. This is in contrast to liquid sterilants which actually kill bacteria by spraying them with heat or chemicals.
Dry-heat sterilization is recommended for items such as instruments that cannot be subjected to high temperatures, liquids that cannot be exposed to direct sunlight, and/or items that do not absorb moisture well. These items should be placed in sealed containers to prevent contamination from escaping during processing.
Dry heat sterilization uses dry heat to sterilize various materials. In this procedure, heated air or fire is employed. The temperature in this procedure is greater than in the wet heat sterilization method. Typically, the temperature exceeds 356°F (180°C). This method is used for items such as instruments that cannot be subjected to water's effects, such as tools made of glass, metal, or hard plastic. This method is also useful for killing bacteria that may be present on objects that will come into contact with food.
Moist heat sterilization uses moisture and heat to kill bacteria. In this process, an item is placed inside a bag or other container with saturated steam. The heat from the steam kills any bacteria that may be present on the item.
There are two main types of dry heat sterilizers: electric and gas. Electric sterilizers use an electric heating element to heat air which is then circulated over the item to be sterilized. Gas sterilizers use gas flames to heat air which is then directed over the item. Both types of sterilizer include a heater, a fan, and ducting system for directing the flow of air through the unit.
In addition to sterilizing medical equipment, dry heat can be used to disinfect items such as dishes, utensils, furniture, clothing, and toys.
The primary distinction between dry heat and moist heat sterilization is that dry heat sterilization refers to sterilization at high temperatures and pressure generated by water steam, whereas moist heat sterilization refers to sterilization at high temperatures and pressure generated by water steam. Dry heat sterilizers include autoclaves and incubators while moist heat sterilizers include steam cookers.
Dry heat sterilizes by the direct action of heat on the material being sterilized. The heat may be applied directly or indirectly. Direct heat means that the heat itself comes in contact with the material being sterilized. Indirect heat means that a surface other than the one being sterilized contacts the material being sterilized. Examples of indirect dry heat sterilizers include autoclaves and incubators. Wet heat sterilizes by using moisture in the form of water vapor or liquid to penetrate the material being sterilized. The moisture is introduced into the object during the sterilizing process through either saturated steam or dry heat. Saturated steam is defined as steam that has been heated to its boiling point or higher. This type of sterilization requires adequate ventilation when used for objects such as food due to the presence of excess moisture which could cause spoilage if not removed.
Wet heat sterilizes by the action of the moisture on the material being sterilized.
List of Instruments
|Hot air oven||used in sterilizing instruments for various aseptic procedures, specially if that can not be autoclaved like powders|
|Koch’s or Arnold’s steam sterilizer||used for steam sterilization|
|A pressure cooker||used as a portable autoclave|
Dryers are classified into three types: vented and ventless.
Red Heat Rest heat sterilization is the method of sterilizing equipment instantly by keeping them in a Bunsen flame until they become red hot. This approach relies on dry heat sterilization, which is routinely used to sterilize devices such as incubation loops, wires, and forceps tips.
The advantage of this method is that it provides a sterile environment for instruments that would otherwise be difficult or impossible to sterilize with other methods. The disadvantage is that red hot objects are reactive and can cause damage to other materials in their vicinity. If an instrument being sterilized with this method needs to be preserved for future use, it must be cooled immediately.
In conclusion, red heat sterilization is a simple method for instantaneously sterilizing equipment that would otherwise be difficult or impossible to sterilize with other techniques. It has the advantage of providing a sterile environment for instruments that would otherwise be difficult or impossible to sterilize with other methods.