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AUTOCLAVEAUTOCLAVE

An autoclave is a device which is used to An autoclave is a device which is used to sterlize all forms of micro-organisms such as sterlize all forms of micro-organisms such as bacteria, fungi, protozoa etc. under high bacteria, fungi, protozoa etc. under high pressure steam at 121˚C or more for 15 to 20 pressure steam at 121˚C or more for 15 to 20 minutes depending on the size of the load and minutes depending on the size of the load and the contents.the contents.

It was invented by It was invented by Charles Chamberland in 1884 and the Charles Chamberland in 1884 and the development of autoclave tremendously development of autoclave tremendously stimulated the growth of microbiologystimulated the growth of microbiology . .

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STERLIZATIONSTERLIZATION

An act of destroying all forms of life on and in An act of destroying all forms of life on and in an object. A substance is sterlize, when it is an object. A substance is sterlize, when it is free of all micro-organisms. Micro-organisms free of all micro-organisms. Micro-organisms can be killed either by physical agents such as can be killed either by physical agents such as heat or by chemical substances regardless of heat or by chemical substances regardless of the manner in which they are killed. the manner in which they are killed. Sterlization is used principally to prevent Sterlization is used principally to prevent spoilage of food and other substances and tospoilage of food and other substances and to

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prevent the transmission of diseases by prevent the transmission of diseases by destroying microbes that may cause them in destroying microbes that may cause them in humans and animals.humans and animals.

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SCHEMATIC DIAGRAM OF SCHEMATIC DIAGRAM OF AUTOCLAVEAUTOCLAVE

OPERATION:OPERATION:

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OPERATION OF AUTOCLAVEOPERATION OF AUTOCLAVE Steam enters through the steam supply and passes Steam enters through the steam supply and passes

into the jacketinto the jacket After the air has been exhausted through the After the air has been exhausted through the

sediment screensediment screen Pressurized steam starts to enter into the chamber Pressurized steam starts to enter into the chamber

and increases the temperature of the chamberand increases the temperature of the chamber Steam circulates among and through the materials Steam circulates among and through the materials

and starts to sterlize themand starts to sterlize them At the conclusion of the cycle, steam is exhausted At the conclusion of the cycle, steam is exhausted

through steam exhausted valve.through steam exhausted valve.

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Autoclaving must be carried out properly. If Autoclaving must be carried out properly. If all air has not been flushed out of the all air has not been flushed out of the chamber, it will not reach 121˚C. the chamber, it will not reach 121˚C. the chamber should not be packed too tightly chamber should not be packed too tightly because steam needs to circulate freely and because steam needs to circulate freely and contact everything in the autoclave. contact everything in the autoclave.

When a large volume of liquid When a large volume of liquid must be sterlized, an extended sterlization must be sterlized, an extended sterlization time will be needed. time will be needed.

e.g. 5litres of liquid may require about e.g. 5litres of liquid may require about 70minutes. 70minutes.

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TYPES OF AUTOCLAVETYPES OF AUTOCLAVE

There are two types of Autoclave:There are two types of Autoclave: Stoves top autoclaveStoves top autoclave Front loading autoclaveFront loading autoclave

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STOVES TOP AUTOCLAVESTOVES TOP AUTOCLAVE

Stoves top autoclaveStoves top autoclave actually resemble a actually resemble a pressure cooker. Each unit comes complete pressure cooker. Each unit comes complete with a bolt-down lid and a pressure gauge on with a bolt-down lid and a pressure gauge on the outside. These units requires an outside the outside. These units requires an outside heat source and can be extremely dangerous in heat source and can be extremely dangerous in untrained hands. They should only be used by untrained hands. They should only be used by experienced professionals.experienced professionals.

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DIAGRAM DIAGRAM

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FRONT LOADING FRONT LOADING AUTOCLAVEAUTOCLAVE

Front loading autoclavesFront loading autoclaves are more widely used are more widely used for their convenience but must also be handled for their convenience but must also be handled with great care. The units are box-shaped and with great care. The units are box-shaped and self contained, equipped with a heating unit to self contained, equipped with a heating unit to turn water into vapour for sterilization. The turn water into vapour for sterilization. The autoclave's controls allow the operator to set autoclave's controls allow the operator to set the desired temperature, and determine how the desired temperature, and determine how long the machine will remain in operation. long the machine will remain in operation. There is also a gauge to track chamber There is also a gauge to track chamber temperature or pressure temperature or pressure

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DIAGRAMDIAGRAM

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PRINCIPLEPRINCIPLE

The The principalprincipal used in autoclave is to increase used in autoclave is to increase the pressure of steam in a closed system that the pressure of steam in a closed system that increases its temperature. The water molecules increases its temperature. The water molecules become more aggregated that increases its become more aggregated that increases its penetration considerably. This principal is penetration considerably. This principal is used to reduce sterlizing time in the laboratory used to reduce sterlizing time in the laboratory instrument called the autoclave. instrument called the autoclave.

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CONSTRUCTIONCONSTRUCTION

It contains a sterlizing chamber into which It contains a sterlizing chamber into which materials are placed and a steam jacket where materials are placed and a steam jacket where steam is introduced. A safety valve decreases steam is introduced. A safety valve decreases excess pressure of the chamber. The excess pressure of the chamber. The temperature rises to 121.5˚C and superheated temperature rises to 121.5˚C and superheated water molecules rapidly conduct heat into the water molecules rapidly conduct heat into the micro-organisms within about 15minutes.micro-organisms within about 15minutes.

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USESUSES

Autoclaves are widely used in:Autoclaves are widely used in: MicrobiologyMicrobiology MedicineMedicine Body piercingBody piercing DentistryDentistry. .

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USESUSES

A notable growing application of autoclaves is in A notable growing application of autoclaves is in the treatment and sterilization of waste, such the treatment and sterilization of waste, such as pathogenic hospital waste. Machines in this as pathogenic hospital waste. Machines in this category largely operate under the same category largely operate under the same principles as the original autoclave in that they principles as the original autoclave in that they are able to neutralize potentially infectious are able to neutralize potentially infectious agents by utilizing pressurized steam and agents by utilizing pressurized steam and superheated water.superheated water.

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CODESCODES

There are some standards which are used for There are some standards which are used for designing the autoclaves:designing the autoclaves:

ASME ASME (American society of mechanical engineers)(American society of mechanical engineers)

This society generates boilers & pressure vessel code. This society generates boilers & pressure vessel code. ASTM ASTM (American society for testing and materials)(American society for testing and materials)

This society generates specifications for most of the This society generates specifications for most of the materials used in the ASME boilers & pressure vessel materials used in the ASME boilers & pressure vessel code. code.

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MATERIAL OF MATERIAL OF CONSTRUCTIONCONSTRUCTION

The selection of the materials from which the The selection of the materials from which the autoclave is fabricated turns entirely upon the autoclave is fabricated turns entirely upon the application.application.

For steam autoclaves, carbon steel is used to For steam autoclaves, carbon steel is used to prevent rusting that occurs with repeated prevent rusting that occurs with repeated cycles of steam, water and air.cycles of steam, water and air.

Above 750 °F (399 °C), high-temperature Above 750 °F (399 °C), high-temperature alloys are used sush as MONEL400 and alloys are used sush as MONEL400 and SA516 Carbon steel. SA516 Carbon steel.