Autoclaves
An autoclave is a chambered device designed to remove contaminants and bacteria from surgical instruments, implants, and other items for patient care. It is the reason the autoclave was invented. Over time, it has become important for other industries besides medicine.
Industrial autoclaves are used in the manufacturing, testing, and certifying of parts that are essential components for various types of machinery. The ability to create pressure in a controlled environment helps to determine if a part can endure stressful conditions as well as its lifetime of use. The convenience of the autoclave is its ability to simulate hazardous conditions without endangering workers or final users. Being able to create stressful environments and gain data makes the autoclave a valuable tool for research, design, and experimentation.
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Who Invented the Autoclave Machine?
The steam digester, a prototype of the autoclave, better known as a pressure cooker, was invented by French physicist Denis Papin in 1679. It was designed to extract fat from bones so the bones could be made into bone meal. Much like the autoclave, the steam digester used confined steam to generate pressure.
Charles Chamberland, known for accidentally discovering a vaccine for cholera due to an error in a laboratory experiment, was a member of the team of scientists who worked with Louis Pasteur in developing a filtration system for solutions containing bacteria. In 1879, he designed a device that would later become the autoclave.
Robert Koch, one of the first microbiologists, devised the first non-pressure steamer in 1881, which was the beginning of the science of disinfection and sterilization. His invention optimized the penetration of moist heat or steam, which was a more efficient means of sterilization than dry heat. At the time of Koch’s invention, boiling was used to sterilize hospital instruments, gowns, and dressings.
In 1933, modern autoclave technology was introduced with the first pressure steam sterilizer that measured the temperature in the chamber drain line or thermostatic trap. Prior to this advancement, pressure was the only means of control of the atmosphere in the chamber, making it impossible to verify the temperature or whether the air was eliminated. Over time, autoclave technology has developed pre-vacuum cycles and the steam-flush pressure-pulse. These advances have produced the devices used in hospitals, industry, and businesses today. The advanced seal on the chamber, elimination of air, and improved pressure systems make the autoclave the ideal sterilization and testing device.
In the middle of the twentieth century, manufacturers began using autoclaves to bond, test, and produce parts for a variety of industries. Autoclave companies that specialized in the health and medical industries had to revise their paradigm and broaden their perspective with the realization that there was a larger market for their product. In the beginning, a small number of companies specialized in autoclaves as an addition to their business model. Today, it is a growing industry developing new uses and technology for autoclave use.
How Does an Autoclave Work?
In healthcare facilities, autoclaves are used to sterilize medical instruments. Equipment to be sterilized is placed in a pressure chamber that uses steam under pressure to eliminate contaminants. The operation of an autoclave depends on three factors: time, temperature, and steam.
The three phases of the autoclave process are:
- Conditioning Phase (C)
- Air inhibits sterilization and must be removed from the chamber during the first phase of the sterilization cycle, known as conditioning. In dynamic air removal steam sterilizers, a vacuum system is used to eliminate air. Steam flushes and pressure pulses are other ways of achieving the same result, while gravity-style sterilizers use steam to displace the air and force it down the sterilizer drain.
- Exposure Phase (S)
- In the exposure phase, items are held at the sterilization temperature for a required length of time to reach complete decontamination. In this phase, the sterilizer drain has been closed while steam is continuously admitted into the chamber, increasing the pressure and temperature inside.
- Exhaust Phase (E)
- The final phase of the cycle is exhaust, where the sterilizer drain is opened, and steam is removed, depressurizing the chamber and allowing the load to dry.
Quality steam is vital to a successful autoclave sterilization process. It is composed of 97% steam vapor and 3% liquid water or moisture, which is the recommended ratio for the most efficient heat transfer. When the steam moisture content is less than 3%, the steam is described as superheated or dry, which is not sufficient heat transfer for maximum sterilization.
What is the Industrial Use of an Autoclave?
The industrial use of an autoclave takes several forms. Since it is a pressure device, it can be used to bond metals, wood, and plastics together. In the case of airplane parts that require a very tight seal, the parts to be bonded are loosely attached by an adhesive and then placed under pressure in the autoclave to form a lasting airtight bond. Unlike medical uses, industrial autoclaves are designed to eliminate pockets of air, bubbles, and tightening connections by using other forms of gas, other than steam, to create the necessary pressure.
Most medical autoclaves can fit on a counter or set like a washing machine in the corner of a room. Industrial autoclaves can be the size of a room, semi-truck, or airplane, depending on their function. Though users may be interested in eliminating contaminants, the main concern is developing a well-sealed product that will not deteriorate or disassemble during use.
Research and development may use an autoclave to test a concept that requires a pressured environment. In this case, contaminants need to be eliminated so that they do not influence the final results. Strict safety standards have been established for this use of industrial autoclaves because of the possible dangers and hazards.
What is the Autoclave Temperature Range?
It is important that an autoclave reach a boiling point to create the necessary pressure for sterilization of medical items or the production of a product. The recommended temperatures are 250° F (121° C), 270°F (132°C), or 275°F (135° C) for the eradication of microorganisms and decontamination. Autoclaves for the industry may need a wider range of temperatures depending on the type of manufacturing and the needed pressure. Manufacturers of autoclaves provide specific guidelines regarding the appropriate settings to achieve maximum results for the purpose of the device.
What is the Autoclave Cycle Time Frame?
Multiple scientific tests have determined the necessary time and temperature for proper steam sterilization used in the exposure phase. The time for industrial use is set by engineers who have determined the interval needed for the product. The periods of exposure vary with the size, shape, weight, density, and composition of the load. Other factors come into play depending on the type and size of the autoclave. Treatment of large industrial autoclaves has to meet exacting standards with specified cycle time frames.
How Big is an Autoclave?
The size and capacity of the autoclave will depend on how it will be used. In a dental office, an autoclave may sit on a countertop to sterilize small packs of instruments. An immediate-use sterilizer may be located near an operating room where it is available to process 1-3 trays of instruments at a time. Most healthcare facilities have large autoclaves in a separate Sterile Processing Department (SPD), which can process 1520 trays of instruments per cycle or up to 625 lbs. of instruments depending on the size of the autoclave.
Most industrial autoclaves are very large and capable of handling large loads. Since daily production is important, the size and number of items to be pressurized varies between industries. Tire industry autoclaves that look like diving bells are capable of handling several dozen tires at one time. In specialized industries, like aerospace, they pressurize fewer parts at once and meticulously inspect every part after pressurization.
What is Autoclavable?
Autoclavable items must be capable of withstanding high temperatures, moisture, and pressure. Manufacturers stipulate the items that can be safely treated and offer assistance in training in the use of the device. Instruments used in medical procedures such as surgical tools, implants, drapes, and linens, or any instrument that has contact with human tissue or fluids need to be sterilized in an autoclave. In these cases, proper sterilization is necessary to avoid microbial contamination, which could lead to an infection.
There is a wide variety of items that are autoclavable in manufacturing. They range from giant truck tires to seals on airplane wings. In most industries, the autoclave is specifically designed for its purpose, with settings established for best results. With this in mind, whatever is put in an industrial autoclave has already been designated as autoclavable.
How Much Does an Autoclave Cost?
When making the decision to purchase an autoclave, there are multiple factors to consider beyond the monetary investment. In the initial evaluation, it is important to determine how the device will be used. In this aspect of the purchase, thought has to be given to the size, which includes the overall size as well as the dimensions of the chamber. The requirements of hospitals and laboratories are considerably different for a medical or dental office as well as an industry. As hard as manufacturers try, they have not been able to come up with a formula that can assist in the buying decision. It is the practical considerations of the purchasing agent that determines the final choice.
An autoclave is like any other piece of equipment and will require regular maintenance. For hospitals, this is a must since sterilization is vital to the health of patients. Autoclaves tend to get a tremendous amount of use and need to be checked regularly. Some manufacturers will include maintenance agreements for parts and labor in the purchasing contract. Regardless of the circumstances, maintenance and upkeep have to be part of the buying decision, much like a car or home. Depending on the autoclave manufacturer, the costs per cycle, utility consumption, and maintenance costs vary and should be evaluated in relation to the total cost-of-ownership. A very vital factor in the purchasing decision for medical facilities, aside from maintenance, is the cost of sterility assurance and monitoring products designed to provide critical information about the autoclave’s sterilization processes and measure the device's bioburden.
The specification for an industrial autoclave is well established prior to making the purchasing decision. Design, function, and requirements are clearly defined before accepting bids. The negotiations, in this case, are between the engineers of the manufacturer and the purchasing company. What is needed is clearly outlined as well as the manufacturer’s timeline for delivery.
Industrial Autoclaves vs. Medical Autoclaves
The autoclave was originally designed to solve the problem of contaminated medical tools. Its invention was a leap forward for the health industry, providing a way to give patients the best possible care and ensure that what touched them was clean, disinfected, and free of disease. Its introduction has led to the prevention of innumerable problems associated with hospital care and treatment. They have become so essential for the practice of medicine that the Food and Drug Administration (FDA) has guidelines for manufacturers as well as testing stipulations for hospitals, which are expected to have a sterilization unit in place in proper working order.
A very common use of autoclaves is in scientific research and pharmaceutical laboratories, where experiments must be exceptionally sterilized to prevent contamination of the results. Unlike medical uses, research facilities use autoclaves to sterilize liquids, an extra measure to eliminate potential contaminants. As with medical autoclaves, research devices have guidelines for safety and proper operation.
It took several years for the industry to see the application of the autoclave. The food industry was the first to see its potential and has used it for years to seal and preserve food. Tire manufacturers rely on the autoclave’s ability to produce pressure to remove bubbles and imperfections from tires. Industries that produce laminates coated materials, or need to produce items with a tight seal have become very reliant on the efficiency and quality that can only be found in an autoclave.
What began as a way to remove fat from bones has become a major part of the industrial world. It seems as though we have only begun to tap the uses of this unique tool.