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 making an informed decision.

In this article, we’ll guide you through everything you need to know about autoclave machines, including common types, costs, applications, and more.

What Is an Autoclave Machine?

An autoclave machine — also known as a steam sterilizer — is a specialized pressure chamber designed to sterilize equipment, materials, and waste through the application of high-pressure saturated steam. Autoclaves leverage the principle that moist heat delivered in the form of steam can rapidly and reliably eliminate microorganisms, including bacteria, viruses, fungi, and spores, when maintained at elevated temperatures and pressures for a set period of time. This process is known as steam sterilization, and it is one of the most effective and widely used sterilization methods¹ in both industrial and clinical settings.

Though autoclave machines come in various sizes and configurations, from small tabletop units to large capacity units with walk-in chambers, their underlying function is the same. In a typical cycle, the autoclave chamber seals, air is removed via gravity displacement or vacuum system, and steam is introduced and heated to temperatures ranging from 250° F to 275° F (121° C to 135° C). Once the autoclave has met sterilization parameters for the required time, it exhausts the steam and dries the load.

Autoclaves are indispensable for a broad range of applications across industries, including:

• Healthcare Facilities: Hospitals, ambulatory surgery centers, clinics, and doctor’s offices all use autoclaves to sterilize surgical equipment and medical devices, ensuring they’re safe for patient contact.
• Research and Academic Laboratories: University and private-sector labs rely on autoclave machines to sterilize instruments, growth media, glassware, and even biohazardous waste before disposal.
• Pharmaceutical and Biotech Manufacturing: These industries employ large, validated autoclave systems to maintain aseptic production environments and comply with stringent regulatory standards.
• Food Production Facilities: The food and beverage industry uses autoclaves to sterilize packaged products, guaranteeing that they’re safe for consumption and extending their shelf life.
• Cannabis Production Facilities: Both medical and recreational cannabis growers leverage autoclaves for tissue culture cultivation, micropropagation, and to sterilize tools and packaging materials.
• Mushroom Growth Farms: Autoclave machines play a vital role in sterilizing growth media and equipment, particularly during substrate preparation, to prevent microbial contamination and ensure a healthy crop.

Autoclave machines are vital wherever sterility, safety, and material performance are mission-critical.

The History of the Autoclave Machine

The history of the autoclave begins with its precursor, the steam digester, invented by French-born physicist Denis Papin² in 1679. The steam digester was essentially an early version of the pressure cooker, though its significance extended beyond culinary applications. More specifically, the steam digester was able to generate higher temperatures than conventional boiling water by using steam under pressure; this principle would become the foundation for steam sterilization.

Fast forward to the invention of the first true autoclave in 1879 by physicist and biologist Charles Chamberland.³ Chamberland, one of Louis Pasteur’s earliest associates, designed a disinfection chamber that applied the same principle as Papin’s steam generator to kill harmful pathogens. This advancement revolutionized sterilization, as it proved far more effective than previous methods, such as dry heat or boiling water. With this invention, autoclaves became critical equipment for healthcare facilities and laboratories, setting the stage for continuous improvements in sterilization technology.

Both 1958 and 1987 marked additional milestones in the history of the autoclave machine with the development of the pre-vacuum cycle and the steam-flush pressure pulse, respectively, which became industry standards.

The late 20th and 21st centuries brought further advancement in sterilization technology, particularly in the areas of automation and sustainability. Autoclave manufacturers began to incorporate features such as programmable cycles, water- and energy-saving technology, data logging, and cycle monitoring into their equipment.

How Does an Autoclave Work?

Autoclaves work by using steam under pressure to sterilize a variety of materials, eliminating harmful microorganisms that could compromise safety or quality. The steam sterilization process hinges on a combination of heat, moisture, and pressure to break down the cell walls of bacteria, viruses, fungi, and spokes.

The Science Behind Steam Sterilization

To kill microorganisms with heat, you must raise the temperature high enough to cause a breakdown of proteins in the cell walls, effectively destroying the cell. Steam is incredibly efficient at transferring heat, which makes it an ideal medium for sterilization. This is because steam contains more energy than air at the same temperature.

When water turns into steam, it absorbs a significant amount of energy — 540 kcal per liter of water — during the phase change from liquid to gas. This is called the heat of vaporization. When steam contacts a cooler object, it condenses back into water, releasing this stored energy and transferring it directly to the item being sterilized. This process is far more effective than using air, which transfers heat at a much slower rate.

The Steam Sterilization Process

Whether it’s a small tabletop unit or a larger, bulk sterilizer, the steam sterilization process breaks down into three key phases:

1. Purge Phase: Steam enters the autoclave chamber and displaces the air, pushing it out through a purge valve. As the chamber fills with steam, both the temperature and pressure begins to rise.
2. Exposure (Sterilization) Phase: The autoclave’s control system closes the exhaust system, trapping the steam inside and enabling the temperature and steam to rise to the desired setpoint. The chamber maintains this high temperature — usually between 250° F to 275° F (121° C to 135° C) — for a predetermined duration, known as the dwell time. During this phase, the heat energy from steam is transferred to the load.
3. Exhaust Phase: Once the sterilization cycle is complete, pressure is released from the chamber through an exhaust valve, and the interior pressure returns to ambient levels. The load remains hot, and steam is vented out of the autoclave chamber.

Sterilization Cycles

Different loads require different sterilization conditions, which is why autoclaves offer a variety of sterilization cycles tailored to specific needs. The four main types of cycles are:

• Gravity Cycle: In a gravity cycle, steam displaces air by gravity through a drain port. The most basic type of autoclave cycle, it’s commonly used to sterilize glassware, unwrapped goods, red bag waste, and other non-porous items.
• Pre-vacuum/Post-vacuum Cycle: These cycles mechanically remove air from the autoclave chamber via vacuum pulse before introducing steam. This ensures steam can penetrate porous materials more effectively, reaching areas that gravity alone might not. Pre- and post-vacuum cycles are often used for wrapped goods, animal bedding, cages, and porous items.
• Liquids Cycle: A liquids cycle is a modified gravity cycle with a slower exhaust rate to prevent boil-over during the sterilization of liquids such as media, broths, or water.
• Immediate-use Cycle: This cycle, which uses higher temperatures (over 270° F/132° C), is ideal for situations that call for rapid sterilization. Immediate-use cycles, sometimes called flash cycles, are often used for unwrapped goods or tools that need to be sterilized on demand.

There are, of course, a variety of cycles beyond those mentioned above, including:

• Steam-air-mix cycles, which are designed to avoid damaging sealed containers such as syringes and test tubes
• Air-over-pressure cycles, which use a combination of steam and air pressure to sterilize items that may be damaged by the moisture in pure steam
• Low temperature cycles, which operate at lower temperatures to sterilize heat-sensitive materials
• Rapid pool cycles, which quickly lower the temperature and pressure inside the autoclave chamber, enabling users to safely handle goods without excessive wait times

What Materials Are Autoclavable?

Autoclave machines are versatile tools, capable of sterilizing a wide range of materials; however, not all materials are suitable for autoclaving, as some may be damaged by the high temperatures, pressures, or steam involved. No matter what material you’re autoclaving, be sure to space out goods to allow for steam penetration throughout the load.

Category	What Can Be Autoclaved	Prep Instructions
Glassware	Glass containers, beakers, flasks, test tubes, petri dishes	Ensure glassware is free of cracks before autoclaving and place containers without lids upside down to prevent air pockets from forming.
Metals	Surgical instruments, metal trays	Rinse all instruments before loading to ensure they’re free from debris.
Plastics	Polypropylene, polycarbonate, fluorpolymers, polyetheretherketone	Check the manufacturer’s instructions for use (IFUs) for each plastic item, as not all plastics are autoclave-safe. Use the low temperature cycle for sensitive plastic items.
Textiles	Surgical gowns, towels, drapes	Properly package textiles to allow for steam penetration and avoid overloading the autoclave to ensure proper circulation.
Rubber and silicone	Gaskets, tubing, seals	Some materials may degrade with repeated exposure to high temperatures and steam, so consult IFUs for the maximum number of cycles a rubber or silicone item can endure.
Liquids	LB broth, water, nutrient solutions	Use a liquids cycle to prevent boil-over. Make sure containers are not sealed tightly to allow steam to escape and be cautious when removing goods from the chamber after the cycle is complete, as they may be hot and under pressure.
Biohazardous materials	Petri dishes, culture plates, contaminated tools, red bag waste	Use appropriate packaging, such as biohazard bags or sterilization pouches, to contain materials.

Under no circumstances should you autoclave flammable materials (such as certain solvents and alcohol-based solutions), aerosol cans or pressurized containers, and items that cannot tolerate moisture, such as electronic components.

The Different Types of Autoclaves

Autoclave machines are available in a wide variety of configurations, each designed to meet the needs of different industries and applications. Here’s a breakdown of the different steam sterilizer categories, and which autoclaves belong in each one.

Class	Class N	Uses gravity displacement to remove air, which is pushed out of the chamber by steam as it enters
	Class B	Uses vacuum pump to remove air from autoclave chamber before sterilization begins, allowing for efficient steam penetration
	Class S	Hybrid of Class N and Class B; offers more flexibility in terms of what goods can be sterilized
Function	Vertical	Characterized by their vertically oriented chambers, which open at the top; often compact in size
	Horizontal	Characterized by horizontally oriented chambers, which open at the side; ideal for high-capacity sterilization
	Pass-through	Characterized by doors on either side of the chamber; designed for environments with strict control over sterilization zones
	Hinged	Characterized by a single door with a radial-arm hinge that allows for easy opening and closing
	Front-loading	Characterized by a horizontally oriented chamber and front-facing door for easy access
	Tower	Characterized by two vertically stacked chambers; compact in size yet ideal for high-capacity sterilization
Capacity	Small	Also known as benchtop or tabletop autoclaves; chamber volumes range from 1–45 liters
	Medium	Chamber volumes range from 45–200 liters; offers flexibility for a wide range of applications
	Large	Chamber volumes with capacities exceeding 200 liters; built for high-volume, large-scale sterilization

Autoclave Costs: Acquisition vs. Operating

Acquiring an autoclave machine is a significant investment for any facility and understanding the total cost of ownership is crucial to making an informed purchasing decision. The total cost of ownership for an autoclave consists of not only the initial acquisition cost but also operating and maintenance expenses that can add up over time.

Let’s break down some of the costs associated with owning and operating an autoclave machine.

Autoclave Procurement Costs

The cost of purchasing an autoclave can vary significantly depending on several key factors:

• Autoclave Size: The larger the chamber, the higher the cost. Autoclaves range from small benchtop models to large industrial units, with prices reflecting their size and capacity.
• Door Type: Single-door units tend to be less expensive than double-door models, which are necessary for environments that require additional capacity (tower autoclaves) or strict separation between sterile and non-sterile zones (pass-through autoclaves).
• Steam Generator: Some autoclaves require an added steam generator if house steam is unavailable, which will add to the purchase price.
• Materials Selection: Premium materials used for construction, such as stainless steel, can increase your investment cost.
• Sterilization Cycle Type: Autoclaves equipped with advanced cycles such as pre-vacuum or high-speed cycles tend to be more expensive than standard gravity displacement models.
• Additional Features: Extra features, such as bioseal options or customizations, also contribute to the overall price.

Typical autoclave models and customization options include:

• Standard single-door autoclave
• Standard double-door autoclave
• With steam generator option
• Stainless steel options
• With bioseal option

One way to offset autoclave acquisition costs is to purchase a refurbished unit, though it’s important to ensure that it’s thoroughly inspected and still capable of meeting your facility’s needs.

Start-up and Training Costs

Once you’ve purchased your autoclave machine, there are costs associated with getting it up and running. These include:

• Installation: Your vendor should provide an installation service, which may include equipment setup and configuration.
• End User Training: Training costs may vary depending on the complexity of the unit and the number of personnel involved.

It’s important to work with your vendor to confirm that these costs are included in the total purchase price. Additionally, look for an autoclave unit with an easy-to-use control system to reduce the amount of time — and cost — spent on end user training.

Utilities Costs

Autoclaves require significant amounts of water, electricity, and steam to operate, and these utility costs can accumulate over time.

• Water: Autoclave machines consume substantial amounts of water for steam generation, effluent cooling, and vacuum generation, contributing to high utility bills.
• Energy: Autoclaves also consume energy to generate steam and maintain the required temperature and pressure for sterilization. Models with energy-saving features, such as auto-idle shutoff, can significantly reduce overall energy consumption.

Maintenance Costs

Maintenance is key to ensuring your autoclave operates efficiently and can extend its life span. However, it comes with its own set of costs, including annual or semi-annual inspections, equipment upgrades, and replacement parts.

For reference, here are some common replacement parts:

• Door switch
• Flat door rod lock
• Door gasket
• Heating element gasket
• Generator gasket O-ring
• Chamber drain strainer
• Swing check valve
• Safety valve
• Solenoid repair valve
• Contactor
• High limit pressure switch

Having a preventative maintenance plan can help reduce the likelihood of needing costly repairs, as well as prevent unexpected downtime.

In the market for a new autoclave? Read this eBook first to learn the 17 questions you should ask prospective vendors to make an informed purchasing decision.

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