Typical loads include laboratory glassware, surgical instruments, medical waste, patient care utensils, animal cage bedding, and Lysogeny broth.
A notable growing application of autoclaves is in the pre-disposal treatment and sterilization of waste material, such as pathogenic hospital waste. Machines in this category largely operate under the same principles as the original autoclave in that they are able to neutralize potentially infectious agents by utilizing pressurized steam and superheated water.How Does an Autoclave Work?
An autoclave sterilizes items by heating them with steam to a very high temperature. Some common temperatures at which autoclaves operate are: 115 degrees C/10 p.s.i., 121 degrees C/15 p.s.i., and 134 degrees C/30 p.s.i. (p.s.i.=pounds per square inch). The temperature, pressure and time of operation depend on the degree of sterilization needed.What Does an Autoclave Kill bacteria?
An autoclave using standard settings can kill most bacteria, spores, viruses and fungi (all models of Osworld Autoclaves). Most doctor's offices, tattoo parlors, dentist offices and other places where instruments might come in contact with contaminants have a small autoclave on site for disinfection (Osworld Portable Autoclave). Hospitals use larger autoclaves that look similar to industrial dishwashers to sterilize many items at once (Osworld Rectangular/Cylindrical Horizontal Autoclave). Heat kills microorganisms by causing vital proteins to coagulate. The proteins stick together causing fatal damage to the microorganism. An autoclave cooks microorganisms in the same way a pressure cooker cooks food, but at a higher temperature. Autoclaves use steam instead of dry heat because steam can more effectively transmit heat to the microorganisms.Air Removal
It is very important to ensure that all of the trapped air is removed, as hot air is very poor at achieving sterility. Steam at 134 °C can achieve in 3 minutes the same sterility that hot air at 160 °C takes two hours to achieve. Methods of achieving air removal include:
Downward displacement (or gravity type) - As steam enters the chamber, it fills the upper areas as it is less dense than air. This compresses the air to the bottom, forcing it out through a drain. Often a temperature sensing device is placed in the drain. Only when air evacuation is complete should the discharge stop. Flow is usually controlled through the use of a steam trap or a solenoid valve, but bleed holes are sometimes used, often in conjunction with a solenoid valve. As the steam and air mix it is also possible to force out the mixture from locations in the chamber other than the bottom.
Steam pulsing - Air dilution by using a series of steam pulses, in which the chamber is alternately pressurized and then depressurized to near atmospheric pressure.
Vacuum pumps - Vacuum pumps to suck air or air/steam mixtures from the chamber.Autoclave Sterilization Graph
Autoclave Quality Assurance
Sterilization bags/pads often have a "sterilization indicator mark" that typically darkens when the bag/pad has been processed. Comparing the mark on an unprocessed bag to a bag that has been properly cycled will show an obvious visual difference. There are physical, chemical and biological indicators that can be used to ensure an autoclave reaches the correct temperature for the correct amount of time.
Chemical indicators can be found on medical packaging and autoclave tape, and these change color once the correct conditions have been met. This color change indicates that the object inside the package, or under the tape, has been processed. Some computer-controlled autoclaves use an F0 (F-nought) value to control the sterilization cycle. F0 values are set as the number of minutes of equivalent sterilization at 121 °C (250 °F) at 15 psi (100 kPa) above atmospheric pressure for 15 minutes . Since exact temperature control is difficult, the temperature is monitored, and the sterilization time adjusted accordinglyTypes of Sterilizers
a) Clinical sterilizer: Designed to process medical devices or medicinal products
b) Laboratory Sterilizers:are designed to process laboratory goods and materials that are neither medical devices nor medicinal products and are not intended for use in the clinical care of patients.Sterilants:
Sterilizers can also be classified according to the sterilant used to effect sterilization. The commonly used sterilants are:
a) high-temperature steam.
b) dry heat (hot air).
c) low-temperature steam and formaldehyde (LTSF).
d) ethylene oxide (EO).
The High-Temperature Steam is the sterilant of choice because of its superior sterilizing qualities. The various High Temperature Steam Sterilizers that Osworld manufactures is shown herein.