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Sterilization is moist heat in the form of saturated steam under pressure. The purpose is to expose each item to direct steam contact at a required temperature and pressure for a specified time to destroy microorganisms that may contaminate a product or container.
Nash utilizes vacuum in the four main types of sterilization, which are: steam sterilization, hydrogen peroxide plasma sterilization, ethylene oxide sterilization, and formaldehyde gas sterilization. Our vacuum systems optimize production with high reliability and energy efficiency.
Steam sterilization is a simple, yet effective decontamination method. Sterilization is achieved by exposing products to saturated steam at high temperatures. Products are placed in a device called the autoclave and heated through pressurized steam to kill microorganisms.
No living thing can survive direct exposure to saturated steam at 250°F (120°C) longer than 15 minutes. Heat destroys microorganisms, but this process is hastened by the addition of moisture in the form of steam. The pressure is necessary to increase the temperature of the steam for sterilization.
Steam must penetrate every fiber and reach every surface of the items to be sterilized. When steam enters the sterilizer chamber under pressure, it condenses upon contact with cold items. This liberates heat, simultaneously heating and wetting all of the items in the load. Thus, providing the two requisites: moisture and heat.
Steam sterilization occurs in three steps. The first step being pre-treatment where all air is evacuated, using a vacuum pump, and replaced with steam. Whereas sterilization is the step where the goods are heated by introducing steam and having it condense on all surfaces, heating and humidifying the spores. The last step of steam sterilization is post-treatment. This process evacuates steam by applying a deep vacuum and is often called the drying phase because the condensate boils from the vacuum process.
Another major type of sterilization is hydrogen peroxide plasma, which requires low-temperature sterilization. Low-temperature sterilization is more delicate on the life of the equipment but effectively sterilizes all germs.
During hydrogen peroxide plasma sterilization, hydrogen peroxide is activated to create a reactive plasma or vapor. The cloud of plasma created consists of ions, electrons, and neutral atomic particles that produce a visible glow. The plasma and vapor phases of hydrogen peroxide are highly effective at killing microorganisms, even at low concentrations and temperatures.
The type of vacuum applied in hydrogen peroxide sterilization are:
• Sealing the articles to be sterilized into the vacuum chamber
• Evacuating the vacuum chamber
• Creating a gas discharge plasma
• Injecting reactive agent into the vacuum chamber
• Diffusing reactive agent
• Partially evacuating the vacuum chamber
• Generating a reactive agent plasma
• Removing gas or vapor from the articles in the chamber
• Venting gas into the vacuum chamber
• Evacuating the vacuum chamber
• Removing the sterilized articles from the chamber
Ethylene oxide sterilization is another method of sterilization. Ethylene oxide or EO is used to sterilize substances that would be damaged by high-temperature techniques, such as pasteurization or autoclaving. When used as a gas, EO gas must have direct contact with microorganisms to be sterilized. Since EO gas is highly flammable and explosive in the air, it must be used in an explosion-proof-sterilizing chamber in a controlled environment. This process typically takes 16-18 hours for a complete cycle.
EO gas sterilization is dependent upon four primary variables: EO gas concentration, temperature, humidity, and exposure time. The sterilization chamber has most of its oxygen removed to prevent an explosion. The chamber is then flooded with a mixture of ethylene oxide and other gases which are later aerated.
The basic steps of ethylene oxide sterilization are:
• Deep vacuum
• Humidification
• Gas admission
• Sterilization
• Pulse post vacuum
• Aeration
• Equalization
Another low-temperature method for sterilization is formaldehyde gas sterilization, which is for heat-sensitive items. Formaldehyde is used as a fumigant in gaseous form. Formaldehyde sterilization is complex and less efficacious than other methods of sterilization. This technique should only be used if steam under pressure will damage the item to be sterilized and ethylene oxide is not available.
Lastly, ozone gas sterilization sterilizes by oxidation, a process that destroys organic and inorganic matter. Ozone is an unstable gas but can be easily generated from oxygen. A 6% to 12% concentration of ozone continuously flows through the chamber. The penetration of ozone may be controlled by the vacuum in the chamber or enhanced by adding humidity. As completion of exposure time, oxygen is allowed to flow through the chamber to purge the ozone. Depending on the size of the chamber load, cycle time could be up to 60 minutes.
Nash is a leading global provider of engineered vacuum solutions and is the premier choice to support customer-specific demands of the sterilizer and autoclave industry. Our vacuum systems are rugged in construction with lower water consumption and associated utility costs. Moreover, Nash liquid ring vacuum pumps are highly-engineered and provide the following benefits:
• Handle process carryover or recycled gas, which increases operating efficiency and reduces operating costs
• Long design life for the highest reliability
• No internal lubrication required results in less maintenance and downtime
• No metal to metal contact for simple operation with wear-free performance
• Incoming vapor is condensed; therefore, smaller, less costly equipment can be selected
• Only one moving part for simple and trouble-free operation
• Proven energy-efficient design that lowers operating costs
NASH vacuum liquid ring pumps are tested per HEI standards; thus, ensuring top quality and avoiding operational downtime.
Backed by over 110 years of experience, NASH certified experts provide aftermarket support with maintenance, service, parts, and repair. Service centers are globally located to protect your vacuum system investment and provide quality, reliable and efficient solutions.
