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40-415: Interest in the material in the 1950s arose from its high melting point and tensile strength, making it more desirable than the more common form of polyethylene. For example, the medical community in 1958 was eager to use Marlex 50 crystalline polyethylene which softens at 260 °F (127 °C). Objects made of Marlex could be sterilized in high-temperature autoclaves without affecting their form. Marlex

80-477: A piston or turbine to perform mechanical work . The ability to return condensed steam as water-liquid to the boiler at high pressure with relatively little expenditure of pumping power is important. Condensation of steam to water often occurs at the low-pressure end of a steam turbine, since this maximizes the energy efficiency , but such wet-steam conditions must be limited to avoid excessive turbine blade erosion. Engineers use an idealised thermodynamic cycle ,

120-401: A heat-resistant bacterium, Geobacillus stearothermophilus . If the autoclave does not reach the right temperature, the spores will germinate when incubated and their metabolism will change the color of a pH -sensitive chemical. Some physical indicators consist of an alloy designed to melt only after being subjected to a given temperature for the relevant holding time. If the alloy melts,

160-1308: A similar thermal oxidation process is still generally mandated for pathological waste and other very toxic or infectious medical waste. For liquid waste, an effluent decontamination system is the equivalent hardware. In dentistry, autoclaves provide sterilization of dental instruments. In most of the industrialized world medical-grade autoclaves are regulated medical devices . Many medical-grade autoclaves are therefore limited to running regulator-approved cycles. Because they are optimized for continuous hospital use, they favor rectangular designs, require demanding maintenance regimens, and are costly to operate. (A properly calibrated medical-grade autoclave uses thousands of gallons of water each day, independent of task, with correspondingly high electric power consumption.) Autoclaves are used in education, research, biomedical research, pharmaceutical research and industrial settings to sterilize lab instruments and glassware, process waste loads prior to disposal, prepare culture media and liquid media, and artificially age materials for testing. Although autoclaves produced for use in medicine may be used in research settings, labs may opt for "research-grade" autoclaves. These are specifically designed for non-medical applications. Research autoclaves often use

200-506: A sub-group of steam engines. Piston type steam engines played a central role in the Industrial Revolution and modern steam turbines are used to generate more than 80 % of the world's electricity. If liquid water comes in contact with a very hot surface or depressurizes quickly below its vapour pressure , it can create a steam explosion . Steam is traditionally created by heating a boiler via burning coal and other fuels, but it

240-467: A temperature-entropy diagram or a Mollier diagram shown in this article, may be useful. Steam charts are also used for analysing thermodynamic cycles. In agriculture , steam is used for soil sterilization to avoid the use of harmful chemical agents and increase soil health . Steam's capacity to transfer heat is also used in the home: for cooking vegetables, steam cleaning of fabric, carpets and flooring, and for heating buildings. In each case, water

280-668: A wide range of designs and sizes, and are frequently tailored to their use and load type. Common variations include either a cylindrical or square pressure chamber, air- or water-cooling systems, and vertically or horizontally opening chamber doors (which may be electrically or manually powered). Research-grade autoclaves may be configured for "pass-through" operation. This makes it possible to maintain absolute isolation between "clean" and potentially contaminated work areas. Pass-through research autoclaves are especially important in BSL-3 or BSL-4 facilities. In order to sterilize items effectively, it

320-485: A “jacketless” design where steam is generated directly in the pressure chamber using heating coils (rather than relying on a “steam jacket” and independent steam generator, as is the case in high-throughput medical autoclaves). Research-grade autoclaves do not have to meet stringent requirements associated with sterilizing instruments that will be directly used on humans. Instead they can prioritize efficiency, programming flexibility, ease-of-use, and sustainability. In 2016,

360-689: Is water vapour ( water in the gas phase), often mixed with air and/or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling , where heat is applied until water reaches the enthalpy of vaporization . Steam that is saturated or superheated (water vapor) is invisible; however, wet steam, a visible mist or aerosol of water droplets, is often referred to as "steam". When liquid water becomes steam, it increases in volume by 1,700 times at standard temperature and pressure ; this change in volume can be converted into mechanical work by steam engines such as reciprocating piston type engines and steam turbines , which are

400-416: Is a machine used to carry out industrial and scientific processes requiring elevated temperature and pressure in relation to ambient pressure and/or temperature . Autoclaves are used before surgical procedures to perform sterilization and in the chemical industry to cure coatings and vulcanize rubber and for hydrothermal synthesis . Industrial autoclaves are used in industrial applications, especially in

440-449: Is also possible to create steam with solar energy. Water vapour that includes water droplets is described as wet steam . As wet steam is heated further, the droplets evaporate, and at a high enough temperature (which depends on the pressure) all of the water evaporates and the system is in vapour–liquid equilibrium . When steam has reached this equilibrium point, it is referred to as saturated steam . Superheated steam or live steam

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480-422: Is available in many sorts of large factory, such as paper mills . The locomotive's propulsion used pistons and connecting rods, as for a typical steam locomotive. These locomotives were mostly used in places where there was a risk of fire from a boiler's firebox, but were also used in factories that simply had a plentiful supply of steam to spare. Steam engines and steam turbines use the expansion of steam to drive

520-412: Is critical. Chemical indicators on medical packaging and autoclave tape change color once the correct conditions have been met, indicating that the object inside the package, or under the tape, has been appropriately processed. Autoclave tape is only a marker that steam and heat have activated the dye. The marker on the tape does not indicate complete sterility. A more difficult challenge device, named

560-400: Is heated in a boiler, and the steam carries the energy to a target object. Steam is also used in ironing clothes to add enough humidity with the heat to take wrinkles out and put intentional creases into the clothing. As of 2000 around 90% of all electricity was generated using steam as the working fluid , nearly all by steam turbines. In electric generation, steam is typically condensed at

600-481: Is important to use optimal parameters when running an autoclave cycle. A 2017 study performed by the Johns Hopkins Hospital biocontainment unit tested the ability of pass-through autoclaves to decontaminate loads of simulated biomedical waste when run on the factory default setting. The study found that 18 of 18 (100%) mock patient loads (6 PPE, 6 linen, and 6 liquid loads) passed sterilization tests with

640-457: Is required to manually perform steam pulsing at certain pressures as indicated by the gauge. A medical autoclave is a device that uses steam to sterilize equipment and other objects. This means that all bacteria , viruses , fungi , and spores are inactivated. However, prions , such as those associated with Creutzfeldt–Jakob disease , and some toxins released by certain bacteria, such as Cereulide , may not be destroyed by autoclaving at

680-489: Is so slow at the lower temperatures in the less extreme environments occupied by humans that it is unlikely they could compete with other organisms. None of them are known to be infectious or otherwise pose a health risk to humans; in fact, their biochemistry is so different from that of humans, and their multiplication rate is so slow, that microbiologists need not worry about them. Autoclaves are found in many medical settings, laboratories, and other places that need to ensure

720-448: Is steam at a temperature higher than its boiling point for the pressure, which only occurs when all liquid water has evaporated or has been removed from the system. Steam tables contain thermodynamic data for water/saturated steam and are often used by engineers and scientists in design and operation of equipment where thermodynamic cycles involving steam are used. Additionally, thermodynamic phase diagrams for water/steam, such as

760-418: Is used for energy storage , which is introduced and extracted by heat transfer, usually through pipes. Steam is a capacious reservoir for thermal energy because of water's high heat of vaporization . Fireless steam locomotives were steam locomotives that operated from a supply of steam stored on board in a large tank resembling a conventional locomotive's boiler. This tank was filled by process steam , as

800-446: Is used in piping for utility lines. It is also used in jacketing and tracing of piping to maintain the uniform temperature in pipelines and vessels. Steam is used across multiple industries for its ability to transfer heat to drive chemical reactions, sterilize or disinfect objects and to maintain constant temperatures. In the lumber industry, steam is used in the process of wood bending , killing insects, and increasing plasticity. Steam

840-620: Is used to accentuate drying of concrete especially in prefabricates. Care should be taken since concrete produces heat during hydration and additional heat from the steam could be detrimental to hardening reaction processes of the concrete. In chemical and petrochemical industries , steam is used in various chemical processes as a reactant. Steam cracking of long chain hydrocarbons produces lower molecular weight hydrocarbons for fuel or other chemical applications. Steam reforming produces syngas or hydrogen . Used in cleaning of fibers and other materials, sometimes in preparation for painting. Steam

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880-522: Is very important to ensure that all of the trapped air is removed from the autoclave before activation, as trapped air is a very poor medium for achieving sterility. Steam at 134 °C (273 °F) can achieve a desired level of sterility in three minutes, while achieving the same level of sterility in hot air requires two hours at 160 °C (320 °F). Methods of air removal include: Stovetop autoclaves used in poorer or non-medical settings do not always have automatic air removal programs. The operator

920-488: The Rankine cycle , to model the behaviour of steam engines. Steam turbines are often used in the production of electricity. An autoclave , which uses steam under pressure, is used in microbiology laboratories and similar environments for sterilization . Steam, especially dry (highly superheated) steam, may be used for antimicrobial cleaning even to the levels of sterilization. Steam is a non-toxic antimicrobial agent. Steam

960-401: The steam digester was created by Denis Papin in 1679. The name comes from Greek auto- , ultimately meaning self, and Latin clavis meaning key, thus a self-locking device. Sterilization autoclaves are widely used in microbiology and mycology , medicine and prosthetics fabrication, tattooing and body piercing , and funerary practice . They vary in size and function depending on

1000-479: The Bowie-Dick device after its inventors, is also used to verify a full cycle. This contains a full sheet of chemical indicator placed in the center of a stack of paper. It is designed specifically to prove that the process achieved full temperature and time required for a normal minimum cycle of 134 °C for 3.5–4 minutes. To prove sterility, biological indicators are used. Biological indicators contain spores of

1040-705: The Office of Sustainability at the University of California, Riverside (UCR) conducted a study of autoclave efficiency in their genomics and entomology research labs, tracking several units' power and water consumption. They found that, even when functioning within intended parameters, the medical-grade autoclaves used in their research labs were each consuming 700 gallons of water and 90 kWh of electricity per day (1,134MWh of electricity and 8.8 million gallons of water total), because they consumed energy and water continuously, even when not in use. UCR's research-grade autoclaves performed

1080-418: The author calculated that using jacketed autoclaves for research tasks translated into an additional $ 74,000 in annual excess spending for UAB. In addition, jacketed autoclaves had a higher initial purchase price than non-jacketed equivalents (37% more). The author also noted anecdotal reports of electrical utility and maintenance cost savings associated with non-jacketed autoclaves. Research autoclaves display

1120-447: The best possible physical properties are repeatable. Manufacturers of spars for sailboats have autoclaves well over 50 feet (15 m) long and 10 feet (3 m) wide, and some autoclaves in the aerospace industry are large enough to hold whole airplane fuselages made of layered composites. A thermal effluent decontamination system functions as a single-purpose autoclave designed for the sterilization of liquid waste and effluent. It

1160-465: The change will be visible. Some computer-controlled autoclaves use an F 0 (F-nought) value to control the sterilization cycle. F 0 values are set for the number of minutes of sterilization equivalent to 121 °C (250 °F) at 103 kPa (14.9 psi) above atmospheric pressure for 15 minutes. Since exact temperature control is difficult, the temperature is monitored, and the sterilization time adjusted accordingly. Steam Steam

1200-556: The end of its expansion cycle, and returned to the boiler for re-use. However, in co-generation , steam is piped into buildings through a district heating system to provide heat energy after its use in the electric generation cycle. The world's biggest steam generation system is the New York City steam system , which pumps steam into 100,000 buildings in Manhattan from seven co-generation plants. In other industrial applications steam

1240-415: The manufacturing of composites. Many autoclaves are used to sterilize equipment and supplies by subjecting them to pressurized saturated steam at 121 °C (250 °F) for 30–60 minutes at a pressure of 205 kPa or 2.02 atm (about double atmospheric pressure) depending on the size of the load and the contents. The autoclave was invented by Charles Chamberland in 1879, although a precursor known as

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1280-439: The media to be sterilized and are sometimes called retort in the chemical and food industries. Typical loads include laboratory glassware, other equipment and waste, surgical instruments, and medical waste . A notable recent and increasingly popular application of autoclaves is the pre-disposal treatment and sterilization of waste material, such as pathogenic hospital waste. Machines in this category largely operate under

1320-569: The most common load and sterilization tasks used by their researchers campuswide. UAB found that jacketed autoclaves consumed significantly more water (44–50 gallons per cycle) and house steam (25–41 pounds per cycle) than non-jacketed autoclaves, which used less than 2 gallons of water and no house steam per cycle, regardless of cycle type or task. The higher water use by jacketed autoclaves resulted in an estimated water cost of $ 764 per jacketed autoclave per year, compared to $ 23 for non-jacketed autoclaves. With over 100 steam-jacketed autoclaves on campus,

1360-461: The optimized parameters compared to only 3 of 19 (16%) mock loads that passed with use of the factory default settings. There are physical, chemical, and biological indicators that can be used to ensure that an autoclave reaches the correct temperature for the correct amount of time. If a non-treated or improperly treated item can be confused for a treated item, then there is the risk that they will become mixed up, which, in some areas such as surgery,

1400-442: The same principles as conventional autoclaves in that they are able to neutralize (but not eliminate) potentially infectious agents by using pressurized steam and superheated water. Autoclaves are also widely used to cure composites, especially for melding multiple layers without any voids that would decrease material strength, and in the vulcanization of rubber. The high heat and pressure that autoclaves generate help to ensure that

1440-408: The same tasks with equal effectiveness, but used 83% less energy and 97% less water. The University of Alabama at Birmingham (UAB) completed a similar study in 2023 in order to assess the performance differences between similar-sized jacketed and non-jacketed autoclaves performing identical tasks in a research setting. They monitored side-by-side autoclaves in a facility running cycles indicative of

1480-437: The steam to penetrate the load evenly. Autoclaving is often used to sterilize medical waste prior to disposal in the standard municipal solid waste stream. This application has become more common as an alternative to incineration due to environmental and health concerns about the combustion by-products emitted by incinerators, especially from the small units which were commonly operated at individual hospitals. Incineration or

1520-622: The sterility of an object. Many procedures today employ single-use items rather than sterilizable, reusable items. This first happened with hypodermic needles , but today many surgical instruments (such as forceps , needle holders, and scalpel handles) are commonly single-use rather than reusable items (see waste autoclave ). Because damp heat is used, heat-labile products (such as some plastics ) cannot be sterilized this way or they will melt. Paper and other products that may be damaged by steam must also be sterilized another way. In all autoclaves, items should always be separated to allow

1560-435: The typical 134 °C for three minutes or 121 °C for 15 minutes and instead should be immersed in sodium hydroxide (1M NaOH) and heated in a gravity displacement autoclave at 121 °C for 30 min, cleaned, rinsed in water and subjected to routine sterilization. Although a wide range of archaea species, including Geogemma barossii , can survive and even reproduce at temperatures found in autoclaves, their growth rate

1600-426: Was used by Wham-O for their Hula Hoops in the 1950s, which helped create a market for this form of plastic. It is now an integral part to a wide variety of products and markets around the world. Additionally, it can be used surgically as a reinforcing mesh in inguinal hernia repair . This article about polymer science is a stub . You can help Misplaced Pages by expanding it . Autoclave An autoclave

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