Autoclave Manufacturer in Chennai:-
An autoclave is a pressure chamber used to carry out industrial processes requiring elevated temperature and pressure different to ambient air pressure. Autoclaves are used in medical applications to perform sterilization; and in the chemical industry to cure coatings, vulcanize rubber and for hydrothermal synthesis
Principle of operation:
An autoclave applies both heat and pressure to the workload placed inside of it. Typically, there are two classes of autoclave. Those pressurized with steam process workloads which can withstand exposure to water, while circulating heated gas provides greater flexibility and control of the heating atmosphere.
Processing by autoclave is far more costly than oven heating and is therefore generally used only when isostatic pressure must be applied to a workload of comparatively complex shape. For smaller flat parts, heated presses offer much shorter cycle times. In other applications, the pressure is not required by the process but is integral with the use of steam, since steam temperature is directly related to steam pressure. Rubber vulcanizing exemplifies this category of autoclaving.
For exceptional requirements, such as the curing of ablative composite rocket engine nozzles and missile nosecones, a hydroclave can be used, but this entails extremely high equipment costs and elevated risks in operation. The hydroclave is pressurized with water; the pressure keeps the water in liquid phase despite the high temperature.
The key component of the industrial autoclave is the fast-opening door; this is also the critical component in cost of autoclave construction. On one hand, the operator must be able to open and close the door quickly and easily; on the other, the door must satisfy stringent safety requirements. Such is the quality of autoclave door design that the US experiences as few as an estimated five or six autoclave failures annually.
Autoclave design is driven by various safety standards, foremost among which is the ASME Pressure Vessel Code. While most nations use the ASME code, some have developed their own. The CE standard in Europe applies to vessels as well as to electrical controls, and China requires that pressure vessels comply with their domestic code. All codes specify conservative requirements intended to maximize safety. Local governments may also impose licensing requirements related to autoclave operation.
While the autoclave is not as ubiquitous as the oven, it is typically used in a number of classes of application. Since rubber vulcanizing cannot be done in an air atmosphere, steam is used, and this mandates a pressure vessel of suitable capability. This is a batch process, thus a fast-acting door is necessary. The only practicable means of accomplishing this is an autoclave, and many are used in the rubber products industry. The manufacture of pressure-treated wood may require autoclaves. The sterilization of waste products is yet another application of steam autoclaves.
The aerospace industry manufactures small numbers of very expensive products and is thus able to afford the high capital and unit operating costs of autoclaves. Typically, this entails applying carefully controlled levels of heat and pressure to parts and assemblies. The curing of composites requires compacting the piles of material, pressing this material against the mold, forcing out volatiles and excess resin, and holding everything motionless during the entire cure cycle. In structural adhesive bonding, the autoclave forces the parts together and holds them while the adhesive cures. Unlike a press, the autoclave applies pressure uniformly, irrespective of the shape of the workload.
Autoclave Steam Quality:
When it comes to transferring large quantities of energy to an object requiring sterilization, nothing’s more powerful than steam. After all, steam engines propel ships and trains. Even the Titanic was powered by steam.
We discussed steam quality in a detailed post on sterilization methods, but let’s review the factors that determine this quality, because it’s crucial for proper autoclave functioning and the sterilization process as a whole. Two parameters are most important:
The optimal composition of steam within an autoclave is 3% liquid and 97% gas. Any change in the percentage of moisture increases or decreases sterilization time. In practice, sterilization time is calculated according to optimum steam conditions and steam’s ability to transfer energy to the non-sterile load prior to sterilization. After all, one of the most important benefits of steam autoclave sterilization is that it requires considerably less time and heat than a dry heat sterilizer, due to steam’s capacity to transfer energy.
Industrial and scientific autoclaves:
Although best known as sterilizers, autoclaves can also be used to carry out all sorts of industrial processes and scientific experiments that work best at high-temperatures and pressures. Unlike sterilizing autoclaves, which usually circulate steam, industrial and scientific autoclaves may circulate other gases to encourage particular chemical reactions to take place. Industrial autoclaves are often used for "curing" materials (applying heat to encourage the formation of long-chain polymer molecules). For example:
1.Rubber can be vulcanized (heated, toughened, and hardened with sulfur) in an autoclave.
2.Nylon (a plastic) can be made by "cooking" a concentrated salt solution in an autoclave to encourage what's called condensation polymerization.
3.Polyethylene (polythene, another plastic) can be made by circulating air or organic peroxides through an autoclave to polymerize ethylene.
Airplane materials made from composites are also typically cured in large industrial autoclaves.
Some autoclaves combine elements of both sterilization and industrial manufacture. For example, natural cork (wooden) bottle stoppers have to be boiled and sterilized before they're suitable for use. Traditionally, that was done in large water tanks; now it's much more likely to be done on a large scale in computer-controlled, industrial autoclaves.
Creating the required temperature within the chamber is reached in a number of ways:
1) Steam can be injected into the chamber via an internal steam source such as an integral stainless steel steam generator, which can be built within the Autoclave cabinet or can be supplied as a separate external unit on larger autoclaves.
2) Some laboratories or hospitals have their own direct steam source on site, which would similarly be injected into the chamber.
3) In some Autoclaves heaters are built into the base of the chamber and the water is heated until it boils and produces steam.
The main advantage of using a steam generator (or the direct steam method) is that cycle times can be considerably faster as the steam is immediately available. In basic autoclaves the water is topped up manually by pouring water into the vessel whilst some autoclaves are connected to a direct water supply and the water level is maintained automatically. Some of Astell’s smaller units are available with an integral water tank, which once filled, can run for up to 20 cycles repeatedly before being replenished. In CSSD applications it is a requirement that the steam is dry saturated steam with a known dryness and noncondensable gas content e.g. in the UK, Steam with values within the specification set out in HTM2010.
When the desired temperature is achieved for the required time then the steam supply will cease either by shutting off the power to the heaters or by cutting off the steam supply. Thus the temperature and the pressure will gradually drop. In units with a vacuum system fitted the vacuum pump can be used to remove the steam (i.e where drying is required).
