On This Page On This Page PURCHASE WITH CONFIDENCE Discover the 17 questions you need to ask before buying your next autoclave. Get the Guide 10-Step Guide to Autoclave Temperature and Pressure Written by: Arthur Trapotsis MS Biochemical Engineering, MBA, Consultant Autoclaves sterilize goods using four interdependent variables: temperature, pressure, steam, and time. Understanding how these variables work together — and how disruptions to any one of them can compromise a cycle — is essential to anyone responsible for running a sterilization program. This guide will show you how each element contributes to sterilization, the temperature and pressure ranges used for different load types, and practical advice on how to ensure your autoclaves consistently perform at their best. Key Takeaways: Steam sterilization relies on temperature, pressure, steam, and time. A failure in any one of these can result in a failed cycle. Steam quality is just as important as autoclave temperature and pressure. Saturated steam is necessary for sterilization, while superheated steam is far less effective at killing microorganisms and can damage sterile barrier packaging. Common sterilization temperatures include 250°F (121°C), 270°F (132°C), and 275°F (135°C). The right choice depends on load type, packaging, and cycle configuration. How Autoclave Sterilization Works No matter what setting you’re in or what applications you use an autoclave for, most models rely on a combination of the following four elements to achieve sterilization: Temperature: During a steam sterilization cycle, the temperature of the autoclave rises to a level at which bacteria, viruses, fungi, and spores cannot survive. Steam transfers thermal energy to microorganisms, irreversibly disrupting their proteins and cellular structure through a process known as denaturation. Temperature is the primary driver of microbial kill in an autoclave; all other variables exist in service of achieving and sustaining it throughout the load. Pressure: Steam is a condensable vapor whose temperature and pressure are precisely linked through the steam saturation curve. At any given pressure, saturated steam has a fixed temperature; at any given temperature, it exerts a predictable pressure. This relationship is why we’re able to use pressure as a proxy to verify that steam in the chamber is behaving correctly. Autoclaves are engineered to withstand operating pressures, and their pressure sensors serve as a real-time check on steam conditions. Steam: Steam is the heat-transfer medium that carries thermal energy from the chamber walls to every surface of the load. Because it releases a large amount of latent heat when it condenses on cooler surfaces, steam transfers heat far more efficiently than hot air at the same temperature. That’s why steam sterilization is so much faster than dry heat sterilization. But not all steam is equally effective. The steam used for sterilization must be saturated for optimal heat transfer. Steam heated beyond its saturation point becomes superheated and behaves more like dry air than steam. Superheated steam does not condense efficiently, transfers heat poorly, and can damage sterile barrier packaging. Steam quality, which we’ll cover in greater detail later in this post, is also a critical and often overlooked variable in sterilization outcomes. Time: Sterilization is not instantaneous. Temperature dictates the rate at which microorganisms are destroyed but, even at the ideal temperature, the load must be held at sterilization conditions long enough to achieve the target Sterility Assurance Level (SAL). How long a cycle runs depends on load type, packaging, density, and cycle configuration. Though the actual steam sterilization process is consistent across all autoclave models, different models have different use cases. Some of the most common include: Gravity displacement autoclaves: These are primarily used for processing laboratory media, water, pharmaceutical products, regulated medical waste, and non-porous articles whose surfaces have direct steam contact. High-speed pre-vacuum sterilizers: Ideal for wrapped goods (e.g., surgical packs), pipette tips and other high-density polyethylene products (e.g., syringes), media solutions in containers (e.g., tissue culture flasks), and medical textile items (e.g., textile-based personal protection equipment). Table-top steam sterilizers: These models are mostly used in outpatient, dental, and rural clinics and are designed for small instruments, such as hypodermic syringes, needles, and dental instruments. Bulk sterilizers: Large, room-scale sterilizers are employed mainly at central sterile departments and other high-throughput settings. They are typically constructed into a building, such that the floor of the autoclave chamber is level with the floor of the building, allowing sterile technicians to load goods into the autoclave on rolling racks. It’s important to note that autoclave manufacturers establish temperature and pressure settings, so that each unit arrives with predefined, validated cycles. This way, you don’t have to set the temperature and pressure for each cycle you run. Still, it’s useful to understand the role that these elements play in the sterilization process. Optimizing Temperature for Steam Sterilization While the temperature within the chamber needs to reach a certain threshold to effectively sterilize a load, exact temperature requirements will vary depending on different considerations, namely load type and cycle length. For example, some items — such as thermoplastics, sensitive liquids, and some medical devices — can’t withstand higher heat and must be sterilized at lower temperatures for longer periods of time to maintain integrity of the product. Common temperatures for steam sterilization include: 158°F–212°F (70°C–100°C) is reserved for true low-temperature cycles, which are used for non-heat-stable objects, materials that easily congeal, and materials that shouldn’t be exposed to temperatures higher than atmospheric pressure. Since these cycles are less effective at limiting the total microbial burden of a given load, they’re only suitable for very specific applications in very specific settings. 250°F (121°C) is the common sterilization temperature for wrapped goods where the higher heat of a pre-vacuum treatment is unviable. Cycles at this temperature take significantly longer than cycles at higher temperatures, but the tradeoff may be advisable for more heat-sensitive goods. At 250°F, the corresponding chamber pressure is approximately 15 psi above atmospheric pressure. 270°F (132°C) is typically used for shorter, immediate-use cycles when a single item is urgently needed for a procedure and time for steam to penetrate an entire load is not a concern. At 270°F, the corresponding pressure is approximately 28–30 psi above atmospheric pressure. 275°F (135°C) is reserved for pre-vacuum sterilization of durable items, such as wrapped goods, packs, cages, and porous materials, that can withstand higher temperatures. With any cycle, it’s important to keep in mind that temperature has a direct impact on sterilization outcomes. If the temperature is too low, it may take an extremely long time to achieve full sterilization. Conversely, if the temperature is too high, you risk damage to the items in a load. The relationship between sterilization temperature and time is exponential, with slight changes in temperature having major impacts on time. The Role of Pressure in Steam Sterilization High temperature alone is not enough to achieve sterilization — pressure must also be present. This is for several reasons. Primarily, as steam follows the steam saturation curve, pressure predictably raises the temperature of the steam within the chamber to reach a degree that’s optimal for killing harmful microorganisms. The addition of pressure also makes it possible for liquids to undergo sterilization without boiling. This is because when pressure is raised, so is the liquid’s boiling point, if only temporarily. For example, liquid water can be sterilized at 250°F (121°C), 38°F (21°C) over its normal boiling point as a result of the pressure within the chamber during the sterilization cycle. By slowly reducing the pressure as the liquid cools, it can then be safely removed from the chamber after sterilization. Pressure also has a direct impact on sterilization effectiveness… If the pressure is too high, loads can become damaged, steam can escape or become superheated, and temperatures can become too elevated. If the pressure is too low, the cycle may take too long for loads to achieve sterility, steam may not sufficiently penetrate the load, and temperature may be too low to effectively remove all harmful contaminants. Though these are risks to be aware of, many modern autoclaves have precise pressure controls that ensure the proper pressure is achieved and maintained during sterilization cycles. Additionally, some autoclaves are also equipped with vacuum systems, which enable the unit to apply negative pressure to goods before and after sterilization, aiding in the removal of air and moisture from porous goods. The Importance of Steam Quality Temperature and pressure get most of the attention when we talk about autoclaving, but steam quality is equally critical, and more likely to be the cause of a failed or suboptimal cycle. For steam sterilization to work, steam must be saturated, at or very close to its condensation point, with a vapor-to-moisture ratio of approximately 97% to 3%. When saturated steam contacts a cooler surface in the load, it condenses and releases a large quantity of latent heat. This is the mechanism that actually kills microorganisms. The condensation reaction is rapid and efficient, which is why saturated steam sterilizes faster than dry heat. Two steam quality problems can undermine this process: Wet steam contains more than 3% liquid water. Excess moisture reduces heat transfer efficiency, can cause wet packs (loads that remain damp after the cycle), and may interfere with steam penetration into porous loads. Superheated steam has been heated beyond its saturation point, so it no longer readily condenses on surfaces. An autoclave running on superheated steam functions more like a dry heat sterilizer. At typical autoclave temperatures, superheated steam is less microbicidal than saturated steam and can damage sterile barriers such as peel pouches. The steam saturation curve relationship holds only for saturated steam. If chamber pressure corresponds to a temperature higher than expected from the steam tables, your steam may be superheated. It’s important to measure steam quality as part of autoclave validation, and to re-check after any changes to the steam supply system. Overcoming Autoclave Challenges Maintaining ideal temperature and pressure isn’t without its challenges. For example, let’s say your autoclave didn’t fully pressurize. This could be due to issues with the water supply or heating element, which are inhibiting the unit’s ability to reach its pressure set points. Or it could be issues with the bellows and door gasket allowing pressure to escape the chamber. Similarly, an autoclave may struggle to reach temperature. In this case, check the steam generator to ensure it’s powered on or to inspect any potential damage. If the steam generator is in working order, look to see if the chamber drain is clogged, whether there’s a problem with the steam trap, or a malfunctioning valve. A less obvious though equally important issue to be aware of is steam quality degradation. If autoclave pressure and temperature appear normal, but you’re experiencing biological indicator failures or wet packs, the steam supply could be the problem. Superheated steam or excessive non-condensable gas content in the steam supply can cause cycles to appear normal while actually failing to sterilize the load. If you suspect your autoclave has a steam quality issue, a formal steam quality test is the best diagnostic step. If any of the fixes to these issues involve major repairs, it’s always best to call in a professional to address the problem. 13 Tips for Maximizing Autoclave Performance So how can you ensure you’re getting the most value out of your autoclaves’ performance? These 10 tips are a good place to start: Follow loading best practices, such as allowing for ample room between items, placing empty containers upside down, and being sure not to overload the autoclave. Set up a regular service schedule for your autoclave lineup. When ordering your autoclave, ensure that it’s equipped with the best loading options for the goods you plan to sterilize. Use packaging that allows for full steam penetration and holds up to the temperature of sterilization. Always allow the cooling phase to fully complete before opening the chamber. This is especially critical for liquid loads. Monitor and save cycle records to watch out for any changes in autoclave performance. Validate your existing autoclave lineup using biological indicator tests to ensure a given cycle and load will achieve sterility. Then, document those cycles in a standard operating procedure for consistent results. Validate any newly purchased autoclaves after installation using qualification tests. Regularly run test cycles such as Bowie-Dick and vacuum leak tests. Ensure that your autoclaves’ steam generator and valves are not being taxed and reduce water bills by engaging standard sustainability features. Ensure the water supply feeding your autoclave’s steam generator meets the quality specifications in the manufacturer’s instructions for use. Poor water quality can cause scale buildup, degrade steam quality, and shorten the life of heating elements and other components. Confirm that you’re running the right cycle for the load type. For jacketed autoclaves, allow the unit to fully reach operating temperature before running your first cycle of the day. Autoclave Safety Protocols As autoclaves operate at high temperatures and pressures, they can pose significant risks to user safety. To protect technicians from harm, strict safety practices related to the autoclave should always be in place and followed carefully. At the very least, safety measures should include the following: Personal protective equipment should be worn on eyes and hands at all times while loading and unloading an autoclave. It’s crucial to remember that jacketed autoclaves preheat prior to a cycle being run, so the walls and door of the autoclave will already be at a temperature hot enough to cause contact burns on bare skin, even while loading. Always check the chamber pressure gauge on the front of the autoclave prior to attempting to open the door. Even a small amount of pressure inside the chamber could cause the door to open at force. Materials such as polystyrene, polyethylene, bleach, hypochlorite, and other corrosive chemicals can melt or create hazardous gasses if exposed to the temperatures of steam sterilization. If you would not heat a material past the melting point of water using a bunsen burner, you should not run the material through a sterilization cycle. The pressure inside the autoclave will temporarily raise the boiling point of liquids during a cycle. If a proper liquid cycle (which has a slow pressure ramp-down to allow for cooling) is not run, liquids may boil over or glassware containing liquids may explode when exposed to cooler temperatures following a sterilization cycle. If water pools underneath the autoclave or steam exits the unit while the door is closed or no cycle is running, safety mechanisms may be preventing an unsafe buildup of excess pressure. Immediately engage safety stops and mark the machine as unsafe to use until qualified service personnel can diagnose and address the problem. Keep Your Autoclaves Running at Peak Performance Whether it’s issues related to temperature, pressure, or something else entirely, it’s crucial to avoid running into the problems that can take your autoclaves offline and sideline your facility’s operations. Routine maintenance is essential to ensure that your steam sterilizers continue to function properly for years to come. Download your free copy of our eBook, How to Properly Maintain Your Autoclave, for everything you need to know about keeping your autoclaves in top shape. Have questions? Our team of sterilization experts is here to help. Contact us today to get the answers you need. Frequently Asked Questions Q: What temperature does an autoclave operate at? A: What temperature an autoclave operates at depends on the cycle type and the load you’re processing. The most common sterilizer temperatures are 250°F (121°C), 270°F (132°C), and 275°F (135°C). Lower temperatures require longer exposure times, while higher temperatures can sterilize faster but may damage heat-sensitive items. Low-temperature cycles below 212°F (100°C) can be used to reduce microbial burden but are not appropriate for sterilization in certain settings. Q: Why does an autoclave use both heat and pressure? A: An autoclave uses both heat and pressure because pressure raises the boiling point of water, which allows steam to reach temperatures of 250°F and above, which reliably kill microorganisms. Without elevated pressure, steam cannot sustain the temperatures necessary for sterilization. Pressure also enables autoclaves to process liquid loads without boiling over. The combination of saturated steam, high temperature, and adequate exposure time is essential to sterilization; none of the three is sufficient on their own. Q: What is saturated steam, and why does it matter for sterilization? A: Saturated steam is steam at or near its condensation point, with a vapor-to-moisture ratio of approximately 97% to 3%. Saturated steam condenses on the surface of items in a load, rapidly releasing a large amount of latent heat to kill microorganisms. Q: What causes an autoclave to fail to reach temperature or pressure? A: An autoclave may fail to reach temperature or pressure due to: A problem with the water supply or steam generator preventing adequate steam production A clogged chamber drain blocking air removal and leading to pressure buildup A malfunctioning valve or steam trap A door gasket or bellows leak allowing pressure to escape Steam quality issues such as superheated steam or excess non-condensable gases in the steam supply 17 Questions to Ask Before Buying Your Next Autoclave We created this 17-question eBook as a framework to help you explore and discover the exact type of autoclave best suited to your needs. Get eBook Tweet Like Share
10-Step Guide to Autoclave Temperature and Pressure Written by: Arthur Trapotsis MS Biochemical Engineering, MBA, Consultant Autoclaves sterilize goods using four interdependent variables: temperature, pressure, steam, and time. Understanding how these variables work together — and how disruptions to any one of them can compromise a cycle — is essential to anyone responsible for running a sterilization program. This guide will show you how each element contributes to sterilization, the temperature and pressure ranges used for different load types, and practical advice on how to ensure your autoclaves consistently perform at their best. Key Takeaways: Steam sterilization relies on temperature, pressure, steam, and time. A failure in any one of these can result in a failed cycle. Steam quality is just as important as autoclave temperature and pressure. Saturated steam is necessary for sterilization, while superheated steam is far less effective at killing microorganisms and can damage sterile barrier packaging. Common sterilization temperatures include 250°F (121°C), 270°F (132°C), and 275°F (135°C). The right choice depends on load type, packaging, and cycle configuration. How Autoclave Sterilization Works No matter what setting you’re in or what applications you use an autoclave for, most models rely on a combination of the following four elements to achieve sterilization: Temperature: During a steam sterilization cycle, the temperature of the autoclave rises to a level at which bacteria, viruses, fungi, and spores cannot survive. Steam transfers thermal energy to microorganisms, irreversibly disrupting their proteins and cellular structure through a process known as denaturation. Temperature is the primary driver of microbial kill in an autoclave; all other variables exist in service of achieving and sustaining it throughout the load. Pressure: Steam is a condensable vapor whose temperature and pressure are precisely linked through the steam saturation curve. At any given pressure, saturated steam has a fixed temperature; at any given temperature, it exerts a predictable pressure. This relationship is why we’re able to use pressure as a proxy to verify that steam in the chamber is behaving correctly. Autoclaves are engineered to withstand operating pressures, and their pressure sensors serve as a real-time check on steam conditions. Steam: Steam is the heat-transfer medium that carries thermal energy from the chamber walls to every surface of the load. Because it releases a large amount of latent heat when it condenses on cooler surfaces, steam transfers heat far more efficiently than hot air at the same temperature. That’s why steam sterilization is so much faster than dry heat sterilization. But not all steam is equally effective. The steam used for sterilization must be saturated for optimal heat transfer. Steam heated beyond its saturation point becomes superheated and behaves more like dry air than steam. Superheated steam does not condense efficiently, transfers heat poorly, and can damage sterile barrier packaging. Steam quality, which we’ll cover in greater detail later in this post, is also a critical and often overlooked variable in sterilization outcomes. Time: Sterilization is not instantaneous. Temperature dictates the rate at which microorganisms are destroyed but, even at the ideal temperature, the load must be held at sterilization conditions long enough to achieve the target Sterility Assurance Level (SAL). How long a cycle runs depends on load type, packaging, density, and cycle configuration. Though the actual steam sterilization process is consistent across all autoclave models, different models have different use cases. Some of the most common include: Gravity displacement autoclaves: These are primarily used for processing laboratory media, water, pharmaceutical products, regulated medical waste, and non-porous articles whose surfaces have direct steam contact. High-speed pre-vacuum sterilizers: Ideal for wrapped goods (e.g., surgical packs), pipette tips and other high-density polyethylene products (e.g., syringes), media solutions in containers (e.g., tissue culture flasks), and medical textile items (e.g., textile-based personal protection equipment). Table-top steam sterilizers: These models are mostly used in outpatient, dental, and rural clinics and are designed for small instruments, such as hypodermic syringes, needles, and dental instruments. Bulk sterilizers: Large, room-scale sterilizers are employed mainly at central sterile departments and other high-throughput settings. They are typically constructed into a building, such that the floor of the autoclave chamber is level with the floor of the building, allowing sterile technicians to load goods into the autoclave on rolling racks. It’s important to note that autoclave manufacturers establish temperature and pressure settings, so that each unit arrives with predefined, validated cycles. This way, you don’t have to set the temperature and pressure for each cycle you run. Still, it’s useful to understand the role that these elements play in the sterilization process. Optimizing Temperature for Steam Sterilization While the temperature within the chamber needs to reach a certain threshold to effectively sterilize a load, exact temperature requirements will vary depending on different considerations, namely load type and cycle length. For example, some items — such as thermoplastics, sensitive liquids, and some medical devices — can’t withstand higher heat and must be sterilized at lower temperatures for longer periods of time to maintain integrity of the product. Common temperatures for steam sterilization include: 158°F–212°F (70°C–100°C) is reserved for true low-temperature cycles, which are used for non-heat-stable objects, materials that easily congeal, and materials that shouldn’t be exposed to temperatures higher than atmospheric pressure. Since these cycles are less effective at limiting the total microbial burden of a given load, they’re only suitable for very specific applications in very specific settings. 250°F (121°C) is the common sterilization temperature for wrapped goods where the higher heat of a pre-vacuum treatment is unviable. Cycles at this temperature take significantly longer than cycles at higher temperatures, but the tradeoff may be advisable for more heat-sensitive goods. At 250°F, the corresponding chamber pressure is approximately 15 psi above atmospheric pressure. 270°F (132°C) is typically used for shorter, immediate-use cycles when a single item is urgently needed for a procedure and time for steam to penetrate an entire load is not a concern. At 270°F, the corresponding pressure is approximately 28–30 psi above atmospheric pressure. 275°F (135°C) is reserved for pre-vacuum sterilization of durable items, such as wrapped goods, packs, cages, and porous materials, that can withstand higher temperatures. With any cycle, it’s important to keep in mind that temperature has a direct impact on sterilization outcomes. If the temperature is too low, it may take an extremely long time to achieve full sterilization. Conversely, if the temperature is too high, you risk damage to the items in a load. The relationship between sterilization temperature and time is exponential, with slight changes in temperature having major impacts on time. The Role of Pressure in Steam Sterilization High temperature alone is not enough to achieve sterilization — pressure must also be present. This is for several reasons. Primarily, as steam follows the steam saturation curve, pressure predictably raises the temperature of the steam within the chamber to reach a degree that’s optimal for killing harmful microorganisms. The addition of pressure also makes it possible for liquids to undergo sterilization without boiling. This is because when pressure is raised, so is the liquid’s boiling point, if only temporarily. For example, liquid water can be sterilized at 250°F (121°C), 38°F (21°C) over its normal boiling point as a result of the pressure within the chamber during the sterilization cycle. By slowly reducing the pressure as the liquid cools, it can then be safely removed from the chamber after sterilization. Pressure also has a direct impact on sterilization effectiveness… If the pressure is too high, loads can become damaged, steam can escape or become superheated, and temperatures can become too elevated. If the pressure is too low, the cycle may take too long for loads to achieve sterility, steam may not sufficiently penetrate the load, and temperature may be too low to effectively remove all harmful contaminants. Though these are risks to be aware of, many modern autoclaves have precise pressure controls that ensure the proper pressure is achieved and maintained during sterilization cycles. Additionally, some autoclaves are also equipped with vacuum systems, which enable the unit to apply negative pressure to goods before and after sterilization, aiding in the removal of air and moisture from porous goods. The Importance of Steam Quality Temperature and pressure get most of the attention when we talk about autoclaving, but steam quality is equally critical, and more likely to be the cause of a failed or suboptimal cycle. For steam sterilization to work, steam must be saturated, at or very close to its condensation point, with a vapor-to-moisture ratio of approximately 97% to 3%. When saturated steam contacts a cooler surface in the load, it condenses and releases a large quantity of latent heat. This is the mechanism that actually kills microorganisms. The condensation reaction is rapid and efficient, which is why saturated steam sterilizes faster than dry heat. Two steam quality problems can undermine this process: Wet steam contains more than 3% liquid water. Excess moisture reduces heat transfer efficiency, can cause wet packs (loads that remain damp after the cycle), and may interfere with steam penetration into porous loads. Superheated steam has been heated beyond its saturation point, so it no longer readily condenses on surfaces. An autoclave running on superheated steam functions more like a dry heat sterilizer. At typical autoclave temperatures, superheated steam is less microbicidal than saturated steam and can damage sterile barriers such as peel pouches. The steam saturation curve relationship holds only for saturated steam. If chamber pressure corresponds to a temperature higher than expected from the steam tables, your steam may be superheated. It’s important to measure steam quality as part of autoclave validation, and to re-check after any changes to the steam supply system. Overcoming Autoclave Challenges Maintaining ideal temperature and pressure isn’t without its challenges. For example, let’s say your autoclave didn’t fully pressurize. This could be due to issues with the water supply or heating element, which are inhibiting the unit’s ability to reach its pressure set points. Or it could be issues with the bellows and door gasket allowing pressure to escape the chamber. Similarly, an autoclave may struggle to reach temperature. In this case, check the steam generator to ensure it’s powered on or to inspect any potential damage. If the steam generator is in working order, look to see if the chamber drain is clogged, whether there’s a problem with the steam trap, or a malfunctioning valve. A less obvious though equally important issue to be aware of is steam quality degradation. If autoclave pressure and temperature appear normal, but you’re experiencing biological indicator failures or wet packs, the steam supply could be the problem. Superheated steam or excessive non-condensable gas content in the steam supply can cause cycles to appear normal while actually failing to sterilize the load. If you suspect your autoclave has a steam quality issue, a formal steam quality test is the best diagnostic step. If any of the fixes to these issues involve major repairs, it’s always best to call in a professional to address the problem. 13 Tips for Maximizing Autoclave Performance So how can you ensure you’re getting the most value out of your autoclaves’ performance? These 10 tips are a good place to start: Follow loading best practices, such as allowing for ample room between items, placing empty containers upside down, and being sure not to overload the autoclave. Set up a regular service schedule for your autoclave lineup. When ordering your autoclave, ensure that it’s equipped with the best loading options for the goods you plan to sterilize. Use packaging that allows for full steam penetration and holds up to the temperature of sterilization. Always allow the cooling phase to fully complete before opening the chamber. This is especially critical for liquid loads. Monitor and save cycle records to watch out for any changes in autoclave performance. Validate your existing autoclave lineup using biological indicator tests to ensure a given cycle and load will achieve sterility. Then, document those cycles in a standard operating procedure for consistent results. Validate any newly purchased autoclaves after installation using qualification tests. Regularly run test cycles such as Bowie-Dick and vacuum leak tests. Ensure that your autoclaves’ steam generator and valves are not being taxed and reduce water bills by engaging standard sustainability features. Ensure the water supply feeding your autoclave’s steam generator meets the quality specifications in the manufacturer’s instructions for use. Poor water quality can cause scale buildup, degrade steam quality, and shorten the life of heating elements and other components. Confirm that you’re running the right cycle for the load type. For jacketed autoclaves, allow the unit to fully reach operating temperature before running your first cycle of the day. Autoclave Safety Protocols As autoclaves operate at high temperatures and pressures, they can pose significant risks to user safety. To protect technicians from harm, strict safety practices related to the autoclave should always be in place and followed carefully. At the very least, safety measures should include the following: Personal protective equipment should be worn on eyes and hands at all times while loading and unloading an autoclave. It’s crucial to remember that jacketed autoclaves preheat prior to a cycle being run, so the walls and door of the autoclave will already be at a temperature hot enough to cause contact burns on bare skin, even while loading. Always check the chamber pressure gauge on the front of the autoclave prior to attempting to open the door. Even a small amount of pressure inside the chamber could cause the door to open at force. Materials such as polystyrene, polyethylene, bleach, hypochlorite, and other corrosive chemicals can melt or create hazardous gasses if exposed to the temperatures of steam sterilization. If you would not heat a material past the melting point of water using a bunsen burner, you should not run the material through a sterilization cycle. The pressure inside the autoclave will temporarily raise the boiling point of liquids during a cycle. If a proper liquid cycle (which has a slow pressure ramp-down to allow for cooling) is not run, liquids may boil over or glassware containing liquids may explode when exposed to cooler temperatures following a sterilization cycle. If water pools underneath the autoclave or steam exits the unit while the door is closed or no cycle is running, safety mechanisms may be preventing an unsafe buildup of excess pressure. Immediately engage safety stops and mark the machine as unsafe to use until qualified service personnel can diagnose and address the problem. Keep Your Autoclaves Running at Peak Performance Whether it’s issues related to temperature, pressure, or something else entirely, it’s crucial to avoid running into the problems that can take your autoclaves offline and sideline your facility’s operations. Routine maintenance is essential to ensure that your steam sterilizers continue to function properly for years to come. Download your free copy of our eBook, How to Properly Maintain Your Autoclave, for everything you need to know about keeping your autoclaves in top shape. Have questions? Our team of sterilization experts is here to help. Contact us today to get the answers you need. Frequently Asked Questions Q: What temperature does an autoclave operate at? A: What temperature an autoclave operates at depends on the cycle type and the load you’re processing. The most common sterilizer temperatures are 250°F (121°C), 270°F (132°C), and 275°F (135°C). Lower temperatures require longer exposure times, while higher temperatures can sterilize faster but may damage heat-sensitive items. Low-temperature cycles below 212°F (100°C) can be used to reduce microbial burden but are not appropriate for sterilization in certain settings. Q: Why does an autoclave use both heat and pressure? A: An autoclave uses both heat and pressure because pressure raises the boiling point of water, which allows steam to reach temperatures of 250°F and above, which reliably kill microorganisms. Without elevated pressure, steam cannot sustain the temperatures necessary for sterilization. Pressure also enables autoclaves to process liquid loads without boiling over. The combination of saturated steam, high temperature, and adequate exposure time is essential to sterilization; none of the three is sufficient on their own. Q: What is saturated steam, and why does it matter for sterilization? A: Saturated steam is steam at or near its condensation point, with a vapor-to-moisture ratio of approximately 97% to 3%. Saturated steam condenses on the surface of items in a load, rapidly releasing a large amount of latent heat to kill microorganisms. Q: What causes an autoclave to fail to reach temperature or pressure? A: An autoclave may fail to reach temperature or pressure due to: A problem with the water supply or steam generator preventing adequate steam production A clogged chamber drain blocking air removal and leading to pressure buildup A malfunctioning valve or steam trap A door gasket or bellows leak allowing pressure to escape Steam quality issues such as superheated steam or excess non-condensable gases in the steam supply 17 Questions to Ask Before Buying Your Next Autoclave We created this 17-question eBook as a framework to help you explore and discover the exact type of autoclave best suited to your needs. Get eBook Tweet Like Share
12.10.25 Introducing SterilSteam Sampler, The Steam Condensate Sampler for AAMI ST108 Compliance → Released in 2023, AAMI/ANSI ST108 establishes water quality requirements for water used in the cleaning, rinsing, disinfection, and sterilization of reusable medical devices. In addition to these requirements, ST108 mandates quarterly testing of steam condensate quality to ensure incoming steam does not stain instruments or pose a risk to patient safety. To help healthcare facilities […]
11.6.25 AAMI ST108 & Critical Water for Autoclaves: What ASCs Need to Know → A major step forward in patient safety, ANSI/AAMI ST108 establishes new minimum water quality requirements for water used in the cleaning, rinsing, disinfection, and sterilization of reusable medical devices. Despite providing guidance on water quality management for sterile processing, ST108 has also created confusion, especially regarding test protocols, water treatment, and critical water requirements. In […]
10.20.25 What Is an Autoclave Machine Really Used for? [Applications, Costs & More] → Autoclave machines are mission-critical equipment in a variety of industries, from healthcare to biotech, ensuring equipment and materials are sterilized and safe for use. Whether you’re considering purchasing an autoclave for a new facility, replacing a broken one, or expanding your current sterilization capacity, understanding the ins and outs of autoclave technology is key to […]
