1, whether the cold air is exhausted (sterilizer sterilized before the exhaust cold air, generally exhaust 5min);
2, the sterilization temperature and pressure to meet the requirements;
3, to be sterilized articles Arrangement is too close (affecting the penetration of steam, to be sterilized items need to be loaded into containers, such as media, plug to have a breathable effect, such as cotton balls, can not be sealed);
4, the pressure of steam whether to maintain in the required range (automatic temperature-controlled sterilizers can be automatically maintained at the set temperature, the manual needs to be carefully operated, the temperature is too low, the sterilizing effect is not good, the temperature is too high, the nutritional composition (The temperature is too low, the sterilization effect is not good, the temperature is too high, the loss of nutrients is serious);
5, can be used while sterilizing the exhaust method, that is, after reaching the sterilization temperature and pressure, turn off the exhaust valve, do not shut off the exhaust valve, leave a small slit to continue to exhaust, so that you can not exhaust the cold air to continue to exhaust the exhaust, condensate and exhaust valve for the same pipeline is also able to exclude the condensate).
The above is for reference only.
Ethylene oxide sterilization2007-4-29 Source: China Packaging and Printing Exhibition Network According to the literature, in 1859 AD, Wurtz first discovered the ethylene oxide (ethyleneoxide, referred to as EO), also known as ethylene oxide or oxypropane. But as a disinfectant and sterilizer application is in 1936. 1936, Schrader and Bossert found that EO mixed with CO2, used to kill a variety of pests and bacteria. 1937 Gross and Dixon found that EO on the test of the 48 kinds of microorganisms have a killing effect. 1940 ~ 1943, Griffith and Hull * * * * with the publication of a number of books. Between 1940 and 1943, Griffith and Hull** published several books and applied for patents. 1949, Phillips and Kaye carried out a systematic and more comprehensive study of EO. Since then Ernst and Shull, Ernst and DoyleKereluk and Lloyd, etc. on the sterilization mechanism of EO, influencing factors, acute and chronic toxicity, sterilization effect, corrosiveness and its change in the environment and so on carried out extensive and in-depth research. 1950s EO began to be used in hospital sterilization, according to the survey in the mid-1990s, the United States almost all of the medical institutions have EO sterilization. According to the survey in the mid-1990s, almost all medical institutions in the United States have EO sterilization equipment. And some big cities in China, such as Beijing, Shanghai, Guangzhou, most of the big hospitals have imported EO sterilizers. Due to the latest EO sterilization equipment can provide a very safe guarantee, so EO will remain the main low-temperature sterilization method in the hospital.
1 EO physical and chemical properties
EO is a simple epoxy compounds, molecular formula for C2H4O, molecular weight of 44.05; EO liquid colorless and transparent, with an aromatic ether flavor, can be smelled odor threshold of 500 ~ 700ppm, which means that such as the surrounding environment smells the EO odor, then the air concentration of at least & gt; 500ppm, much higher than the United States NIOSH (NIOSH). Higher than the U.S. NIOSH (Labor Health and Occupational Disease Association) to develop the maximum allowable exposure level of EO. EO is flammable and explosive, the minimum combustion concentration of 3% (30,000 ppm); in order to prevent the explosion and combustion of EO, often adding inert gas. EO at 4 ℃ specific gravity of 0.884, the boiling point of 10.7 ℃, the density of 1.52, therefore, the EO liquid is very easy to evaporate into a gas at room temperature. EO liquid at room temperature is easy to volatilize into gas; EO specific gravity is lighter than water, such as direct discharge of EO into the water, there may be a large number of EO overflow to the surrounding environment, so in general, EO emissions in the hospital can be preferred to the atmosphere. EO can be formed in the presence of water ethylene glycol. Polyethylene or polyvinyl chloride film, 22min can penetrate 0.04mm thick nylon film, 26min can penetrate 0.3mm neoprene cloth, 41min can penetrate 0.39mm thick butyl rubber cloth. Because in order to fully achieve the sterilization effect on the articles, the sterilizing agent must be able to fully contact the various surfaces of the articles (inside, outside, shallow, deep).
Table 1 Steam pressure of EO at different temperatures
Temperature (℃) Steam Pressure (mmHg)
20.0
10.7
20.0
The steam pressure of EO at different temperatures is the same as that at different temperatures, but it is not the only one that can be used.
20.0
25.0
29.0
30.0
50.01.09
760.00
1094.00
1300.00
1500.00
1560.00
2967.00
2 Sterilization principle of EO
EO can kill a variety of microorganisms, including bacterial propagules, germ cells, viruses and fungal spores, and is a broad-spectrum sterilizer. It is generally believed to be due to its ability to interact with microbial proteins, DNA and RNA by non-specific alkylation (non-specificalkylation). EO in aqueous solution can alkylate with the free carboxyl group (COOH group (2NH2), hydrogen sulfide group (2SH) and hydroxyl group (2OH) on proteins, replacing unstable hydrogen atoms to form compounds with the hydroxyethyl root (CH2CH2OH), the protein group is alkylated, so that proteins lose the reaction group needed in the basic metabolism, impeding the normal chemical reaction and metabolism of bacterial proteins, and preventing the bacterial proteins. The alkylation of the protein group deprives the protein of the reactive group needed in the basic metabolism and prevents the normal chemical reaction and metabolism of bacterial proteins, thus leading to microbial death. So far, all the data show that EO bactericidal effect is irreversible, that is to say, EO is a sterilizing agent (sterileagent) rather than a disinfectant (disinfectant). Moreover, according to various clinical and scientific research results, EO is the best sterilizing agent among all chemical disinfectants or sterilizers. EO can inhibit the activity of some microbial enzymes, including phosphatase, peptidase, cholinesterase and cholinesterase. Ethylene oxide also alkylates DNA and RNA, leading to microbial inactivation.
3 Advantages and disadvantages of EO sterilization and the scope of clinical application
3.1 EO (1)Advantages of EO sterilization can be used for the sterilization of items that are not resistant to high temperatures and moisture. (2)Ethylene oxide is considered to be one of the most effective chemical sterilizing agents, which can kill all microorganisms including bacterial germs. (3) strong penetration, can be used in a variety of difficult to penetrate the parts of the sterilization: such as some of the finer, longer catheters with other low-temperature sterilization method is difficult to achieve sterilization, and can only use EO or irradiation. (4) small damage to the goods, because EO kills microorganisms is the use of alkylation principle rather than oxidation process, so the damage to the goods is very small, heat-resistant precision instruments have a very wide range of uses for sterilization. (5) Sterilization, can be wrapped in a variety of wrapping materials, easy to store, transport, open the package can be used to avoid the risk of cross-contamination. (6) There are standard chemical and biological monitoring means, which can effectively control the quality of sterilization, timely detection of sterilization failure of the package. (7) There are decades of experience.
3.2 Disadvantages of EO sterilization (1) the whole sterilization cycle time is longer, the reason is that it takes a long time to ventilate to remove EO residues. (2) EO is toxic, is suspected of carcinogenic, must control the concentration of EO in the indoor air below the national standards. (3) EO is flammable and explosive, storage and sterilization must not leak. Must choose a safe sterilizer, safe operation and storage.
3.3 EO's clinical applications EO has a wide range of clinical uses commonly used in EO sterilization equipment and instruments include: (1) hard and soft endoscopy: arthroscopy, tracheoscopy, cystoscopy, gastroscopy, enteroscopy, mediastinoscopy, fundoscopy, otoscopy, pharyngoscopy proctoscopy, prostatectomy device, thoracoscopy, urethroscopy. (2) Medical equipment: anesthesia equipment, artificial kidneys, diathermy equipment, wires, meter heads, heart-lung machines, respiratory, therapeutic equipment, hemodialysis. (3) Instruments: electric drill, electric burner, electric knife pen, dental drill, microsurgical instruments, nerve stimulator, manometer, surgical instruments, bone drill, needles, artificial joints. (4) Rubber products: catheters, dilators, drains, endotracheal tubes, surgical gloves, sheets. (5) Plastic products: airway intubation, dilators, endotracheal intubation gloves, pacemakers, heart valves, nebulizers, petri dishes, syringes. (6) Other books, toys, linear probes, probes, thermometers, sutures. Therefore EO has been, will be and will remain a predominant method of low temperature sterilization.
4 How to control the key parameters of EO sterilization
The control of the key parameters of the EO sterilization process is to achieve the quality of sterilization to ensure that the key parameters of its sterilization for the concentration of EO, the humidity of the cavity during sterilization, temperature and time. These key factors directly affect the effect of sterilization; each key factor can be different in degree, but each other must reach a balance.
4.1 time gas sterilization is not a rapid process, the sterilization time must be sufficient to kill microorganisms, the length of its time is affected by the following factors: the degree of cleanliness of the sterilized items; microbial wetting and moisture content; the type and density of the packaging materials used; the size of the parcel and the load of the sterilization load; the concentration of EO; the temperature at the time of sterilization; the type of EO gas and so on. Sterilization time varies depending on the material and packaging material of the items contained in the sterilization package, and the sterilization time must ensure that the most difficult items in the load are sterilized to achieve the sterilization effect. Under the same conditions, the sterilization time is also affected by the loading method and the amount of loading. Sterilization pot temperature and EO concentration will also affect the sterilization cycle time; the higher the temperature or EO concentration, the shorter the sterilization time required; low temperature, longer sterilization time or higher EO concentration sterilization time is also affected by the pressure in the pot and the way of EO gas circulation; effective EO gas circulation, can assist the pot load uniform wetting and heating EO gas type is different, sterilization time is different, 100% pure EO gas than EO gas, EO gas is more effective than EO gas. 100% pure EO gas is shorter than EO gas mixture sterilization time. General hospital sterilizer sterilization time for 1 ~ 5h, generally speaking, pure EO sterilization than EO mixed gas sterilization time is shorter, the length of time according to the sterilizer manufacturer's product specification.
4.2 Temperature EO sterilization, temperature affects the rate of microbial killing, it is estimated that the temperature rises 10 ℃, the germ cell killing rate increased by a factor of 1, the temperature can increase the penetration of EO. Hospital sterilizers, generally set the temperature between 49 ~ 60 ℃, a small number of items that can not tolerate this temperature, you can choose between 35 ~ 38 ℃, but at this time it is necessary to increase the concentration of EO or extend the sterilization time. In the sterilization stage of the temperature drop may lead to sterilization failure; in accordance with the requirements of AAMI, the sterilizer temperature error & lt; ± 5 ℃; sterilizer temperature is usually pre-set, often set up two temperatures (eg, 37 ℃ and 55 ℃) for different needs to choose.
4.3 EO concentration EO concentration is usually expressed in mg / L, hospital sterilizers commonly used concentration of 450 ~ 750mg / L, at a certain temperature and relative humidity level, the EO concentration increases (from 50 ~ 500mg / L), microbial kill rate also increased significantly, the sterilization time is also with the concentration of EO to reach its highest point and shorten accordingly. However, EO concentration >500mg/L, did not significantly improve the microbial inactivation rate, and even the reverse side to reduce its killing rate, see Table 2. actual sterilization, due to the consideration of the loss of EO, including EO hydrolysis, adsorption, etc., the choice of concentration should be higher than the relative concentration of the highest point. /p>
700
550
4.4 Relative humidity The water content of the sterilized items, microorganisms themselves, the dry environment and the relative humidity of the sterilization environment of the EO sterilization effect is crucial, such as EO concentration of 600mg / L, the temperature of 54 ℃, relative humidity of 40%, the microbial ability to kill for the relative humidity of 0 10 times. The main reason is: (1) in the alkylation reaction process water is a necessary reaction agent, water and EO reaction to open the epoxy group to promote its role with microorganisms. (2) Water promotes the penetration of EO into the dry EO, and the penetration rate is greatly reduced. (3) Humidification can help to heat the sterilized material to reach the set temperature.
4.4.1 Pre-humidification The sterilized material must first be pre-humidified, generally required to be placed in an environmental condition of 50% relative humidity >2h; step 2 should be to maintain sufficient humidity in the pot to kill microorganisms. A lot of research data has confirmed the inactivation of microorganisms ideal relative humidity is about 30%, but the actual situation, the EO pot body requirements of the relative humidity range of 40% to 80%, in order to ensure that there is enough power to promote the humidity into the package and the goods. However, care must be taken to ensure that there are no water droplets or too much moisture on the sterilized items, so as not to cause dilution and hydrolysis of EO. Bacterial water content and the relative proportion of moisture between the sterilization environment, the sterilization effect of EO also has a significant impact.
4.4.2 humidification mode The more backward way is the cavity plus dehumidification sheet or wet towel, the main disadvantage is that the humidity level is more difficult to control, but also can not heat the goods at present, the new humidification mode is in the negative pressure conditions of the automatic injection of water vapor, this process is also called humidification stage usually takes > 20min. the advantages of the humidity uniformity; humidity level is easy to control; can be heated items. 20 years of the late 1990s introduced the latest version of the sterilization environment, the EO sterilization effect. The late 1990s introduced the latest type of sterilizer equipped with humidity detector, can directly monitor the relative humidity level in the pot, such as can not reach its set minimum relative humidity level, will automatically stop sterilization, re-wetting. Temperature, time, concentration and humidity are the key parameters affecting the effect of EO sterilization, but not like pressure steam and dry heat sterilization, there are ideal parameter values to achieve the effect of sterilization, so it is difficult to specify the exact sterilization parameters.
5 EO sterilization packaging materials requirements
The packaging materials used for EO sterilization at least need to have the following characteristics: must allow the entry of EO sterilizing agent; can withstand a certain degree of humidity; can be easier to remove the EO residue. Common EO packaging materials are listed in Table 3.
Table 3 Packaging Materials for EO Sterilization
Acceptable Packaging Materials Unacceptable Packaging Materials
Peel-Off Pouches
Tyvek
Polyethylene-polyester film
Paper/polyethylene-polyester film
Paper/polypropylene-polyester film< /p>
Polyethylene-plastic bags
Wrapping materials
Cloth
Non-woven fabrics
Paper coated or uncoated
Rigid containers
Plastic boxes with paper or Tyvek lids
Various types of metal foil
Cellophane
PVC
Non-permeable Polypropylene film
Nylon
Glass
6 Toxicity of EO
6.1 Acute Toxicity
6.1.1 Clinical Manifestations Inhalation of large quantities of EO can cause respiratory irritation, dizziness, weakness, nausea and vomiting (either immediately or as an afterthought), chest pain, and neurotoxic reactions. Liquid EO can cause skin irritation, dermatitis and blistering. Eye contact with EO can cause serious eye damage, and splashing of high gas concentrations can cause serious eye irritation and damage. Digestive tract exposure to EO is an uncommon route of exposure. Liquid EO enters the digestive tract and is corrosive, causing severe irritation and burns to the mucous membranes of the digestive tract
6.1.2 First aid treatment
After overexposure to EO, move the patient away from the scene of the poisoning quickly, inhale fresh air immediately, and see a doctor as soon as possible. After skin contact, rinse the contact area with water >15min, remove dirty clothes at the same time, rinse the contaminated area with water and soap, and see a doctor as soon as possible. For eye contact with liquid EO or highly concentrated EO gas, flush eyes for at least 10 min and see a physician immediately. After gastrointestinal exposure, notify a physician or toxicity control center as soon as possible, drink 1 to 2 cups of water, and touch the back of the throat to induce vomiting; a confused person should not be induced to vomit or fed anything.
6.2 Chronic toxicity
6.3 On the chronic toxicity of EO on people, Joyner (1964) has produced EO in a factory survey, the average age of the investigated workers & gt; 10 years, the workshop air EO concentration of 5 to 10 ppm, the results did not find obvious anomalies, and the results of the laboratory did not find evidence of chronic poisoning. The United States NIOSH (National Institute of Labor Health and Occupational Diseases) in the 1980s on the country's 14 factories, 18254 workers exposed to EO cause of death analysis, during this period of the working environment in the TWA of EO (8h average time-weighted concentration) of 4 ppm, the results found that: in addition to leukemia and lymphoma have a slight increase in the mortality rate of other tumors and other chronic diseases is normal. In 1984, in view of the fact that EO is a suspected carcinogen, NIOSH stipulated that the TWA and PEL (Permissible Exposure Level) were reduced from 50ppm to 1ppmAL (Permissible Exposure Level). 1ppm AL (action level) <0.5ppm, 15min sampling exposure <5ppm; if the environmental concentration of EO is lower than the AL, the routine environmental concentration monitoring can be eliminated or reduced.
7 EO emissions and environmental control
7.1 EO safety protection principles EO is a flammable and explosive chemicals, when the concentration in the air >3%, an explosion will occur, the operation of the following safety principles must be observed () to ensure that the sterilizer and the gas cylinder (or gas canisters) away from fires such as matches:1 EO, lighted cigarettes, sparks, and static electricity. (2) EO gas cylinders or gas tanks should be in strict accordance with the state of the relevant flammable and explosive storage requirements. (3) EO sterilization environment in the air concentration to be. ()The workman EO<1ppm4EO staff should be professional knowledge and emergency incident handling training. (5) In accordance with the manufacturer's requirements for regular cleaning, maintenance and commissioning of EO sterilization equipment. (6) EO in the storage bottle, conveying pipeline, sterilization cabinet has a tendency to polymerization, should be frequently cleaned pipeline, sterilizer and storage bottle.
7.2 EO sterilizer installation requirements EO is flammable and explosive poison, so EO sterilizer must be placed in a well-ventilated place, should be avoided in the poor ventilation and space is too small place; do not put the EO pots or tanks close to the source of ignition and try to stay away from the main channel. In order to make the future maintenance and regular maintenance work is convenient, EO pots on all sides (including) above should be reserved 51cm of space, room ventilation system should not be re-circulating type, indoor air exchange should be at least & gt; 10 times an hour, EO sterilization pots should be installed with a special exhaust pipe, and with the building of the other exhaust pipe safety isolation into the room air must be able to flow through the sterilizer, EO pots, and then discharged! Outdoor, as far as possible, there is no dead space. Rest rooms, storage rooms should be far away from the sterilizer and gas cylinders (gas tank storage), such as the availability of appropriate space and local exhaust system, do not need a special room to install the EO sterilizer. Ventilation system should include: (1) room air exchange at least & gt; 10 times per hour, and to ensure that the sterilization area is negative pressure (relative to other work areas). (2) Specialized EO exhaust system. (3) Reasonable air flow. (4) Local exhaust hood.
7.3 EO emissions On EO emissions, the United States EPA (Environmental Protection Agency) in 1994, mainly for commercial sterilization have clear emission regulations, while the hospital does not have clear emission regulations. CFC (Freon) as an explosion-proof agent can prevent the explosion of EO, but due to the destruction of the ozone layer by the CFC, China, the United States and other 22 countries signed the 1987 Montreal Convention, gradually banning the use of CFC (Freon) as an explosive agent, but because of the destruction of the ozone layer. In 1987, China, the United States and other 22 countries signed the Montreal Convention to gradually ban the use of CFC, the United States and other developed countries have banned the use of CFC in January 1996, China has also made clear the timetable for the ban on the use of CFC.
7.3.1 Installation requirements Hospital ethylene oxide emissions preferred atmospheric discharge, installation requirements: (1) there must be a special exhaust piping system. (2) Exhaust pipe material must be EO can not be permeable, such as copper pipe. (3) from the exhaust pipe exhaust port 7.6m range shall not have any flammable or building air intake such as doors, fresh air intake, open windows and so on. (4) If the vertical part of the length of the exhaust pipe & gt; 3m must be installed when the water collector, do not make the exhaust pipe has a depression or back to the circle caused by water and gas accumulation or ice in winter, blocking the pipeline. (5) The exhaust pipe should be guided to the top of the floor, and the outlet reversed downward to prevent water and gas to stay in the pipe wall or cause pipe wall blockage. (6) Professional installation engineers must be hired and installed according to the requirements of the EO sterilizer manufacturer.
7.3.2 Installation method
If the drain can only be discharged into the water, EO overflow will be caused due to air cracks in most drain fixtures. The heat from the sterilizer also creates an upward flow of air that pushes the EO upward. Therefore, it must be absolutely guaranteed that EO gas cannot flow back into the working environment. The following methods can be used: (1) An EO collection box can be installed outside the EO sterilizer exhaust port to remove EO vapors instantly; the EO collection box should surround all open sewers and the entire sewer system must be closed. (2) A liquid/gas separator can be installed so that the liquid can be discharged directly into the sewer and the gas discharged as described above. (3) This exhaust method must be installed in a well-ventilated and preferably unoccupied factory room with negative pressure at the exhaust port. Detoxification method If possible, EO can be detoxified and then discharged. For EO industrial sterilization must be detoxified, while hospital sterilization if no special provisions can be directly discharged into the atmosphere (hospitals use a small amount of EO). Generally, the following detoxification methods can be used: (1) add a catalyst to decompose EO into carbon dioxide and water, and then directly discharged into the atmosphere, this method is particularly suitable for hospitals. (2) Absorbent absorption of EO, this method can only handle a small amount of EO, can be used for exhaust cabinets or temporary emissions. (3) Add acid hydrolysis, concentrated sulfuric acid can be used to make EO decomposition into glycol and carbon dioxide, the industry mainly use this method. (4) Recycling, due to high investment, mainly used for industrial sterilization.
8 EO residue
EO residue mainly refers to the EO sterilization, to stay in the goods and packaging materials within the EO and its two by-products ECH (ethylene chlorohydrin) and EG (ethylene glycol ethane). Exposure to excessive EO residues (especially grafts) can cause burns and irritation in patients, hemolysis, destruction of cells, etc.; affecting the residue of EO is related to the following factors.
8.1 Types of materials
8.2 PVC and polyurethanes absorb high amounts of EO and require long ventilation times; Teflon and nylon absorb very low amounts of EO but are very tightly bound and also require long ventilation times. Polyethylene and polypropylene absorb a moderate amount, but release more easily when ventilated. Metal and glass do not absorb EO at all, so they can be used directly without ventilation, see Table 4.
Table 4 Minimum ventilation time for various items under different conditions (h)
Materials Indoor air (℃) Mechanical ventilation (50℃) Fume cupboard (60℃)
Metal and glass
No package
Wrapped
Wrapped
External rubber
External polyethylene and polypropylene
Plastic except polyvinyl chloride
Polyvinyl chloride
Plastic
Built-in pacemaker
2
24
48
96(4d)
168(7d)
168(7d)
04(21d)
Available immediately
2
8
12
12
12
12
32
2
5
8
8
8
8
24
Note: 3 not wrapped in plastic; 33 wrapped in plastic or in contact with human tissues
8.2 Physical Parameters
On the same material, the thicker the more difficult to discharge the residue. For example, 0.8mm plastic residue discharge rate is 3 times faster than 1.6mm plastic; the same material, the same weight items, the larger the surface area, the easier it is to discharge the residue. Polymer density also affects the EO absorption and discharge, the greater the density, lower absorption, but the combination of tighter, not easy to discharge; and low density is more absorption, discharge easier.
8.3 Packaging, loading and loading capacity The larger the loading capacity, the denser the loading, the tighter and larger the package is discharged more difficult.
8.4 Sterilization and Ventilation Parameters The higher the temperature during ventilation, the shorter the time required.
8.5 Usage of sterilized items Longer ventilation times are required for grafts. Compared with natural ventilation, mechanical ventilation can provide a great guarantee of safety, and short time, do not contaminate the work environment, so the United States hospital EO sterilization is not allowed to use natural ventilation. The United States AAMI standards for mechanical ventilation is: 60 ℃, ventilation 8h; 50 ℃, ventilation 12h; 38 ℃, ventilation 32 ~ 36h. For some special items such as grafts may need to extend the ventilation time. The American AAMI according to the use of different time will be divided into three categories, according to its classification, the development of the maximum residue standards, see table 5. other countries relevant residue standards: France Pharmacopoeia EO residue maximum 2ppm, the German Health Agency EO residue found that the sensitivity of the test method less than 1ppm. China's national standards for disposable medical supplies by the EO bacteria or disinfection of the factory, EO residues
Table 5 U.S. EO and its harmful compounds of the maximum permissible values (ppm)
Name of the device EOECHEG
Intrauterine contraceptive device
Contact lenses
Instrument in contact with mucous membranes
Instrument in contact with the blood (extracorporeal)
In contact with the skin Devices
In vivo implants (>100g)
In vivo implants (10 to 100g)
In vivo implants (<10g)5
25
250
25
250
250
100
< p>251025
250
25
250
250
250
100
2510
500
5000
250
5000
5000
5000
5000
. p>2000
500
Table
9 Types of EO Sterilizers
Hospital EO sterilizers can be classified into two main types: gas-mixed 100% pure EO. In general, modern automatic EO sterilizer must be able to provide four basic parameters of quality control, in order to avoid EO sterilization failure, and a high degree of safety assurance. (1) exposure to EO gas time generally ranging from 18h (mixed gas sterilization time is longer). (2) Sterilization temperature is generally a: hot cycle for 49 ~ 60 ℃, cold cycle for 35 ~ 37.8 ℃. (3) The degree of gas can range from 450 to 1200mg / L. (4) Humidity range within the chamber 30% ~ 70% RH. Therefore, the purchase of EO sterilizer, must fully understand the EO bacteria how to control these key parameters such as the parameters do not meet the standard sterilization,, whether there is a termination of the function?
10 EO sterilizer features
EO sterilizer in the design must have the following features to ensure its safety: (1) door locks automatically closed: EO gas release, the pot door must be automatically closed, the law open. If you need to forcibly abort the cycle, must wait for the EO gas discharge, the pot can be opened. (2) Good sealing of the door: to ensure that the positive pressure sterilization, EO gas leakage. (3) groove gasket: not only to ensure that the door is not easy to open or close the door is not easily damaged by its special closed performance and can ensure that the seal is intact. (4) Final vacuum and pulse washing: after sterilization, final vacuum and pulse washing can effectively remove E residue. (5) Alarm: Once the machine malfunctions, including EO leakage, the machine can give a loud alarm in time. (6) Automatic venting: In case of power failure and other obstacles, the EO can be automatically discharged from the pot. (7)The sterilizer has the dual function of sterilization/ventilation: after the sterilization is completed, it directly enters the ventilation stage, and after the ventilation is completed, the items can be used directly after taking.
10.1 mixed gas type EO sterilizer
EO is a flammable and explosive gas, in order to prevent the explosion of EO combustion, often added to the explosion-proof agents such as CO2 (8.5% EO91.5% CO2), CFC (88% CFC, 12% EO) and so on. As CFC has been stopped, foreign countries have adopted HCFC (8.6% EO, 91.4% HCFC) (U.S. EP regulations in 2030, HCFC will be banned) to temporarily replace the CFC. domestic production of HCFC is still law, and the price of HCFC is more expensive, can only be used as a combination of gas CO2. CO2 as a mixture of gases does not damage the environment, the price of moderate and so on, but the shortcomings are: (1) the price of the gas is not the same as that of the gas. Shortcomings are: (1) two gas mixture (EO and CO2) will produce layering phenomenon, especially when the pressure is insufficient, which may affect the quality of sterilization. (2)EO will form polymer and clog the pipeline. (3) Higher pressure in the chamber during sterilization may easily cause the item to break. (4) Because of the inability to provide sufficient pressure, each bottle of gas can only be used 50%. (5) The gas mixture is supplied in cylinders through a pipeline to the pot, so be sure that there is no possibility of leakage at the pipeline valve. (6) The whole sterilization stage is a positive pressure process. (7)Sterilization time is long.
10.2 100% pure EO gas-type sterilizer
100% pure EO gas is mainly used in small doses of gas canisters (such as the current maximum of less than 100-200g per canister of gas) to reduce the EO explosion and leakage hazards. 100% pure EO sterilizer has the following characteristics: (1) do not need exogenous piping, the EO canisters are placed into the cavity automatically punctured after the release of EO gas. EO gas. (2) Sterilization time is short. (3) The whole sterilization process is negative pressure sterilization, not easy to leak. (4) Gas tank storage should pay attention to safety, to prevent leakage and explosion. At present, the pure sterilization pot is more and more accepted by the majority of hospitals
.