Do You Need a Large Capacity Autoclave? [Or Do You Just Think You Do?]

Arthur Trapotsis
Written by: Arthur Trapotsis

MS Biochemical Engineering, MBA, Consultant

The definition of the word “large” can be subjective — what one person considers massive, another might find diminutive. In the world of steam sterilization, the commonly held wisdom is that any autoclave that requires a pit or is big enough to walk inside of, is considered a “large capacity autoclave” or a “bulk autoclave.” Autoclaves of this size and stature are typically more than 1,000L (36 cubic feet) and reserved for high-volume applications, such as vivarium (animal) cages and biohazard waste sterilization.

In this article, we’ll talk about the different types of large capacity autoclaves, as well as some clever workarounds for facilities that require the processing capacity of (but may not have the available space for) a bulk autoclave.

Most Common Types of Large Autoclaves

Though there are a wide variety of large capacity autoclaves on the market, these models are the most common types used in life science laboratory and healthcare settings:

  • High-capacity Walk-in Autoclaves: This type of large autoclave derives its name from its large chamber — sometimes six feet or more in total height — which allows personnel to physically enter the chamber during loading and unloading.High-capacity walk-in autoclaves typically have an excavated pit beneath the floor of the facility so that the bottom of the sterilizer chamber is level with the floor, making it easier for operators to wheel in carts with racks of goods on them. This functionality eliminates the need for a separate transfer carriage and simplifies loading and unloading. As one can imagine, these autoclaves are designed to sterilize a large volume of goods with a single cycle, which is a major selling point for facilities with high-volume requirements; however, high-capacity walk-in autoclaves rarely include built-in features that can support efficiency, such as shelving.
  • Retorts: A retort is a type of autoclave commonly found in food processing facilities and used to process packaged foods and beverages to extend their shelf life. Compared to other types of large autoclaves, retorts feature an extremely long chamber, often equipped with some form of conveyance system. Goods are either loaded into the chamber on wheeled carts or automatically as part of a larger assembly line. Once in the chamber, goods are heat-treated and sterilized inside of their final packaging.

How to Determine Whether You Need a Large Capacity Autoclave

If you’re thinking about investing in a large autoclave, you’ll need to first consider your load requirements — that is, how many cages do you need to process per day? If you need to fit a bulk autoclave in a tight space, you’ll also want to think about the installation path, and whether there are any tight corners or small doorways the unit will need to fit around to get to its final installation location. Given that some large autoclaves can be as long as 120”, it’s important to take into account the dimensions of hallways, doorways, and even freight elevators.


Not everyone who thinks they need a large capacity autoclave actually does. In many cases, it’s possible to custom-configure a smaller autoclave to accommodate your capacity needs.

Consider the available loading volumes of various chamber sizes to determine which size offers optimal loading capacity. For example, moving from a 24” x 24” x 48” chamber size to a 26” x 26” x 49” chamber may allow you to load an additional row of goods on each shelf, greatly increasing overall capacity at a lower cost than investing in a large capacity autoclave. If you’re unsure whether you truly need a large autoclave, Consolidated’s engineering team is happy to help you run calculations and come up with ways to increase your yield.

What to Do If You Don’t Have Room for a Bulk Autoclave

So, you’ve determined that you do, in fact, need a large capacity autoclave but lack the floor space to accommodate one — what now? The best way to conserve floor space without compromising on processing capabilities is to recess your large autoclave into a wall; this enables the autoclave to sit in a less finished service area and prevents it from taking up unnecessary floor space. For example, it’s common for large capacity autoclaves to be built into the wall of a production facility to provide service access (behind the wall) without sacrificing production floorspace.

UW Vet

Another space-saving tip: It’s best to configure large autoclaves in such a way that service is only required on one side of the unit, as this allows the unit to be placed up against a wall or in a corner, out of the way.

Finally, when designing the layout of your facility, take door swing, control side, and cart and carriage location into account (if applicable). In most cases, you can modify these elements to help a large autoclave fit within a tight location.

Facilities looking to increase their load capacity without having to significantly re-architect would do well to consider multiple “medium sized” freestanding autoclaves — again, medium is a relative term here — that are easier to load and less costly to maintain than a bulk autoclave.

Depending on the manufacturer, it’s possible to customize your medium freestanding autoclave according to your sterilization needs — for example:

  • You can accommodate loading carts and carriages or add internal shelving to maximize capacity and expedite loading and unloading. For example, Consolidated’s autoclaves can be equipped with a wide variety of loading configurations, from units with a single stationary wire shelf to prevent drain blockage — a perfect option for facilities that need to sterilize large, unstructured loads such as hazardous waste bags — to units with integral shelves that maximize internal chamber space for rolling carts and carriages for seamless loading and unloading.
  • Facilities that need to sterilize tall glassware, bioreactors, or other unwieldy instrumentation can look for a unit that is taller than it is wide.
  • Facilities in which operators need to push a fully-loaded wheeled cart and carriage into the chamber or in which cross-contamination from touching the autoclave door handle is a concern can add a vertical sliding door powered by a foot pedal.

Large Capacity Autoclave FAQ

Q: What is a large capacity autoclave?

A: Although one person’s idea of what constitutes a large capacity autoclave may differ slightly from the next, the general rule of thumb is that any autoclave that requires a pit or a dedicated room is considered large capacity.

Q: What types of large capacity autoclaves are available?

A: Though there are a wide variety of bulk autoclaves on the market, the three most common are high-capacity walk-in autoclaves, retorts, and high-capacity freestanding autoclaves.

Q: What can I do if I need the processing capabilities of a large capacity autoclave, but lack the space for one?

A: First and foremost, you might want to ask yourself whether you really need a large autoclave. Many of our customers have come to us thinking that they needed a large autoclave, but found that they were able to achieve the same results — often at a lower cost — with a custom-configured smaller autoclave.

If, however, you really do require a large capacity autoclave, you might want to consider recessing your unit into the wall to conserve floor space or configuring your autoclave so that service is only required on one side of the unit. That way, you can tuck it into a corner.

Q: How do I figure out whether I really need a large capacity autoclave?

A: We’re glad you asked. Our team of engineers can work closely with you to run calculations and increase your yield. We can also walk you through customization options, as well as offer targeted recommendations on space requirements within your facility.

Ready to Make Your Next Autoclave Purchase? Read This, First

An autoclave — especially a large capacity one — is a major investment, one that requires careful consideration. We’ve created this buyers’ guide to help you ask the right questions and make an informed decision.

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Ready to Make Your Next Autoclave Purchase? Read This, First