Sterilizer design, installation, cycle development and verification . temperature and pressure that GMP and Non-GMP Comparison Chart. (Section ). Correct Correlation between Temperature and Pressure shows correct operation of the autoclave and that air purging is satisfactory. NB. This table is accurate at. Autoclave Temperature and Time Pressure Chart. STERILIZER, TEMPERATURE , PRESSURE, TIME. Steam autoclave, C ( F), 15psi, 15min. unwrapped.
They vary in size and function depending on the media to be sterilized and are sometimes called retort in the chemical and food industries.
Autoclave - Wikipedia
Typical loads include laboratory glassware, other equipment and waste, surgical instruments, and medical waste. Machines in this category largely operate under the same principles as conventional autoclaves in that they are able to neutralize potentially infectious agents by using pressurized steam and superheated water.
A new generation of waste converters is capable of achieving the same effect without a pressure vessel to sterilize culture media, rubber material, gowns, dressings, gloves, etc. It is particularly useful for materials which cannot withstand the higher temperature of a hot air oven. Synthetic quartz crystals used in the electronics industry are grown in autoclaves. Packing of parachutes for specialist applications may be performed under vacuum in an autoclave, which allows the chutes to be warmed and inserted into their packs at the smallest volume.
Air removal[ edit ] It 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. Downward displacement or gravity-type: As steam enters the chamber, it fills the upper areas first as it is less dense than air.
This process compresses the air to the bottom, forcing it out through a drain which often contains a temperature sensor.
Only when air evacuation is complete does the discharge stop. Flow is usually controlled by a steam trap or a solenoid valvebut 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. Explained here Superatmospheric cycles: It starts with a vacuum followed by a steam pulse followed by a vacuum followed by a steam pulse. The number of pulses depends on the particular autoclave and cycle chosen.
In medicine[ edit ] Dental equipment in an autoclave to be sterilized for 2 hours at to degrees Celsius A medical autoclave is a device that uses steam to sterilize equipment and other objects. This means that all bacteriavirusesfungiand spores are inactivated. Many procedures today employ single-use items rather than sterilizable, reusable items.Saturation Temperature & Saturation Pressure
This first happened with hypodermic needlesbut today many surgical instruments such as forcepsneedle holders, and scalpel handles are commonly single-use rather than reusable items see waste autoclave. Autoclaves are of particular importance in poorer countries due to the much greater amount of equipment that is re-used. Providing stove-top or solar autoclaves to rural medical centers has been the subject of several proposed medical aid missions.
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 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 raised because of the combustion by-products emitted by incinerators, especially from the small units which were commonly operated at individual hospitals.
In dentistry, autoclaves provide sterilization of dental instruments according to health technical memorandum HTM According to HTM, instruments can be kept, once sterilized using a vacuum autoclave for up to 12 months using sealed pouches. These spores can also be killed at slightly lower temperatures, but longer heat treatment periods must be applied in such cases to arrive at the same summary effect of heat treatment.
From the microbial point of view, it would be ideal to employ very intensive heat treatment which would eliminate the risk of any surviving microorganisms. However, most canned meat products cannot be submitted to such intensive heat stress without suffering degradation of their sensory quality such as very soft texture, jelly and fat separation, discolouration, undesirable heat treatment taste and loss of nutritional value destruction of vitamins and protein components. In order to comply with above aspects, a compromise has to be reached in order to keep the heat sterilization intensive enough for the microbiological safety of the products and as moderate as possible for product quality reasons.
A method was developed for such a balance between food safety and food quality requirements by measuring and quantifying the summary amount of heat treatment to which a canned product is exposed during the entire sterilization process. Cold point in cans with solid a and liquid b content 1 The exception are the group of thermophilic bacillus strains, in particular Bac. The amount of heat treatment applied to a meat product can be measured using the F-value-concept see page Small producers, who are not equipped to employ the F-value concept, are not excluded from producing properly sterilized canned goods.
CANNING / STERILIZATION OF MEAT PRODUCTS
In these cases established technical reference parameters of sterilization temperatures and times to the type of product and to the size of the cans can be employed. The size and format of cans is of utmost importance for the speed of heat penetration. These are approximate values, which can differ slightly depending on the materials filled into the cans. When comparing cans of same volume but different format see Fig. Ways of heat penetration into horizontal a2 and vertical b2 flat cans and square c2 cans with solid not liquid content.
CANNING / STERILIZATION OF MEAT PRODUCTS
Processes and equipment Process The sterilization process in the canned product can be subdivided into three phases see Fig. Vertical retort In autoclaves retorts Fig. The autoclave must be fitted with a thermometer, pressure gauge, pressure relief valve, vent to manually release pressure, safety relief valve where steam is released when reaching a certain pressure e.
The steam supply valve is applicable when the autoclave is run with steam as the sterilization medium or when steam is used for heating up the sterilization medium water. Simple small autoclaves are usually vertical autoclaves Fig. Through the opened lid the goods to be sterilized are loaded into the autoclave. The cans are normally placed in metal baskets. The baskets are placed in the autoclave, either singly or several stapled on top of each other.
Before starting the sterilization, the lid must be firmly locked onto the body of the autoclave. The autoclave and lid are designed to withstand pressures up to 5. These types of autoclaves are best suited for smaller operations as they do not require complicated supply lines and should be available at affordable prices. Larger autoclaves are usually horizontal and loaded through a front lid Fig.
Horizontal autoclaves can be built as single or double vessel system. The double vessel systems Fig. Using the two—vessel system, the heat treatment can begin immediately without lengthy heating up of the processing vessel and the hot water can be recycled afterwards for immediate use in the following sterilization cycle.
Another technology employed is rotary autoclaves in which the basket containing the cans rotates during sterilization. The sterilization process can be kept shorter and better sensory quality of the goods is ensured Fig.
Double purpose equipment for small-scale.
Can be used as cooking vat or autoclave Fig. Large horizontal autoclave At the final stage of the sterilization process the products must be cooled down as quickly as possible. This operation is done in the autoclave by introducing cold water. The contact of cold water with steam causes the latter to condense with a rapid pressure drop in the retort. However, the overpressure built up during thermal treatment within the cans, jars or pouches remains for a certain period Fig.
During this phase, when the outside pressure is low but the pressure inside the containers is still high due to high temperatures there, the pressure difference may induce permanent deformation of the containers.
Pressure inside autoclave blue and inside cans red during heating and cooling phase schematic Fig. Producing counter pressure on cans see arrows inside the autoclave with compressed air Therefore, high pressure difference between the autoclave and the thermal pressure in the containers must be avoided.
This is generally achieved by a blast of compressed air into the autoclave at the initial phase of the cooling Fig.
Sufficient hydrostatic pressure of the introduced cooling water can also build up counter pressure so that in specific cases, in particular where strong resistant metallic cans are used, the water pressure can be sufficient and compressed air may not be needed.
For the stabilization of metallic cans, stabilization rims Fig. Types of containers for thermally treated preserves Containers for heat-preserved food must be hermetically sealed and airtight to avoid recontamination from environmental microflora. Most of the thermally preserved products are in metal containers cans.
They are usually cylindrical Fig. However, other shapes such as rectangular or pear-shaped cans also exist Fig. Tinplate consists of steel plate which is electrolytically coated with tin on both sides.
The steel body is usually 0. The tin layer is very thin from 0. In addition, the interior of the cans is lined with a synthetic compound to prevent any chemical reaction of the tinplate with the enclosed food.
Tin cans consist of two or three elements. In the case of three-piece steel cans, they are composed of the body and two ends bottom and lid Fig.
The body is made of a thin steel strip, the smaller ends of which are soldered together to a cylindrical shape. Modern cans are induction-soldered Fig.
The use of lead soldered food cans was stopped decades ago. Hence the risk of poisonous lead entering canned food no longer exists. Tin cans and aluminium cans of different sizes and shapes Two-piece steel cans have a lid similar to the three-piece cans but the bottom and body consist of one piece, which is moulded from a circular flat piece of metal into a cup.
These cup-shaped parts may be shallow-drawn with short side wall or deep-drawn with longer side walls Fig.