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How Does an Autoclave Work?

How Does an Autoclave Work?

Walk into any laboratory around the world and you are almost certain to find an autoclave sterilizing lab media. Whether the lab is a small pharmaceutical startup, or a large university research facility, sterilizing laboratory media is crucial in carrying out complex scientific research.

Choosing the right autoclave for your laboratory can increase efficiency and lower lab operating costs – but today we look inside the autoclave sterilizer to see just how the sterilization process works. How autoclave sterilization works is a straightforward process; autoclaves operate under a set of scientific principles to carry out a job that is nothing less than critical.

3 Components Needed for an Autoclave to Sterilize

An autoclave is a common piece of laboratory equipment that works to sterilize lab media using three primary components: temperature (heat), pressure, and steam.

1) High Autoclave Temperatures

Precise autoclave temperatures are key in how an autoclave works to create steam and build pressure. The most typical chamber temperature for an autoclave is 121°C. Most commercially available autoclaves will achieve higher temperatures in the 130°-135°C range, including the TOMY Autoclave Sterilizer, which has a maximum temperature of 135°C. Autoclaves work by creating high autoclave temperatures and pressure that create steam to sterilize.

2) High Pressure Builds Up

Similar to a standard pressure cooker, laboratory autoclaves work by producing high pressure. In a food pressure cooker, the high pressure works to quickly cook food. In a laboratory autoclave, the pressure is used to generate enough steam to sterilize the microorganisms present on lab equipment. Inside a TOMY Autoclave, sterilization pressures range from 0.019 to 0.212 MPa.

3) Creates Steam that Sterilizes

The steam generated from the rise in chamber pressure and temperature comes in contact with the media inside, which is where the real autoclave sterilization process begins. The energy transferred from the heat destroys the microorganisms and breaks down cell walls/membranes – creating a sterile environment inside the chamber.

How long does an autoclave take to sterilize?

The easy answer here is it depends. The CDC states “The two common steam-sterilizing temperatures are 121°C (250°F) and 132°C (270°F)”, so it is easy to see the time necessary to sterilize a piece of media differs from object to object. 

Sterilization time depends on the material, its porosity, and whether it is in some type of sterile packaging or wrap. In most laboratory settings, 121°C for 20 minutes will kill contaminants, but please check the specifics for your media type. To sterilize larger pieces of lab media or large volumes of lab media, it will take longer.

TOMY Autoclaves are programmable to sterilize (at 105–135°C temperatures) for up to 10 hours. They are also programmable to heat (at 45–95°C temperatures) for up to 99 hours. A preset timer allows you to delay the start time by up to 99 hours, by setting your autoclave to sterilize at the most convenient time.

How Different Types of Autoclaves Work

There are two primary types of autoclave sterilizers – gravity displacement autoclaves and pre-vacuum autoclaves also called pre-vac for short. These two types of autoclaves move steam in different ways to sterilize the media inside the chamber, including glass, liquid media, and laboratory waste.

How Gravity Autoclaves Work

Gravity autoclaves are fairly basic in their sterilization process. Water at the bottom of the chamber is directly heated to create steam and pressure. This pressurized steam then forces the ambient air, previously in the chamber, out. Once the chamber volume is filled with steam, the autoclave is programmed to close the necessary valves, not allowing any more air to escape the chamber. The autoclave works by continuing to build the pressure and temperature until it reaches the desired settings. At this point, the cycle begins and the sterilization process is underway.

Source: http://www.frankshospitalworkshop.com/equipment/autoclaves_equipment.html
Note: TOMY SX model autoclaves are gravity displacement autoclaves with the chamber oriented vertically to maximize throughput. The image above pictures a horizontal chamber.

How Vacuum Autoclaves Work

Vacuum autoclaves are more complex in their design than gravity autoclaves and are not as commonly used in laboratories. Vacuum autoclaves work by using a vacuum pump that forces the ambient air out of the chamber, allowing steam to enter. This process is repeated several times until the chamber has been completely evacuated of ambient air and filled with steam. Because of the vacuum function “pulling” the ambient air out of the chamber, the steam is allowed to penetrate the media. For this reason, vacuum autoclaves are more suited for fabrics, wrapped items, and sterilization pouches.

Whether used in research, pharmaceutical, or a medical laboratory, it is important to choose the right type of autoclave for your purposes. Check out this video showing more information about the 2 primary types of autoclaves and how to choose the right autoclave for your lab.

For more information on how autoclaves work, contact our technical experts or leave us a message in the comments below.

What Can Be Autoclaved?

What Can Be Autoclaved?

What’s in your autoclave?

What do a pine tree, a bottle of beer, and a cannabis-based product have in common? 

Answer: They all have used Tomy autoclaves in their development.

That’s right. Our autoclaves are used for a lot more than Erlenmeyer flasks and Petri dishes. 

In this article, we’ll explore some of the common—and not-so-common—uses for steam sterilization, a.k.a. autoclaving. Here at Tomy, we’re proud that so many different organizations utilize our products. So we thought we’d give you a little “tour.” 

The usual suspects 

First, a little Autoclave 101. The autoclave combines four factors—heat, steam, pressure, and time—to sterilize what’s placed inside it. It’s the ideal solution for lots of media and is usually far more practical than options such as incineration. 

Laboratories live by autoclaves. Specifically, we’re talking about laboratories where anything, particularly anything microscopic, can grow. This means biochemical and biological research laboratories, as well as pharmaceutical research labs, and lots and lots of government and university labs. They’re all Tomy customers. 

So what are they autoclaving? 

Broadly, they’ll need to clean up used glass media, liquid media, and instruments. So this means lots of glassware (that is, Pyrex/borosilicate glass, as opposed to household glass, which shouldn’t be used), including flasks, beakers, and glass Petri dishes. 

Then there’s the culture media, biological cultures, and stocks. We can’t tell you how many contaminated solid items—such as pipette tips, gloves, and plastic Petri dishes—get autoclaved each day. “Contaminated” is the important word here since the autoclave can handle bacteria, viruses, and fungi with equal aplomb. 

One of the nice things about using glass for containing your culture media is that you can autoclave both of them together at the same time. Simply leave the culture in the glassware, and place it in the autoclave, like a single item. 

Other materials that are autoclave-friendly include, naturally, stainless steel and the proper plastics: polypropylene and polycarbonate. 

By the way, all of those flasks we’d mentioned have two things in common: 1) they’re round, and 2) they’re vertical. While that may seem pretty obvious, it’s something to keep in mind when shopping for an autoclave, because if it’s 1) rectangular or 2) horizontal, you’re going to regret that purchase every time you have a batch of flasks to sterilize. 

There are, of course, items that you should never autoclave. These include: 

  • Anything that’s flammable, corrosive, reactive, toxic (including bleach), or radioactive. You don’t want to expose that to high heat and steam.
  • Paraffin-embedded tissue. 
  • Any liquid in a sealed container. To play it safe, you can fill a container about two-thirds full, and autoclave it with its cap loosened. 

The intriguing outliers 

At Tomy, we’re delighted to include among our clients’ organizations that are at the creative cutting edge of product development—and rely on our autoclaves to help them along. Specifically: 

  • One client sure can see the forest for the trees. That’s because they’re creating pine trees in the laboratory, for later transplanting in the desert, where it would be nearly impossible to get them to germinate from scratch. And so every used petri dish, and its depleted agar, go into the autoclave after the microscopic “crop” is “harvested.” (By the way, that’s not “autoclave,” but rather “autoclaves,” plural. This one lab uses seven in order to keep production flowing smoothly.) 
  • Product development is brewing for another Tomy autoclave client; they make beer. Actually, lots of startup breweries and microbreweries rely on our autoclaves for product development, for everything from lagers to IPAs. Beer, like bread, relies on yeast for a significant portion of its flavor profile. So, you need to cultivate that yeast and experiment with different stocks and strains, until you get it just right for that new product you’re developing. And whereas lots of the bio labs are using culture dishes to run their experiments, our friends in the bottled-beverage world have a firm reliance on bioreactors, those complex containers used to cultivate yeasts. We mention these because they’re the ultimate perfect fit for our SX series of autoclaves: tall and cylindrical. 
  • The cannabis industry is growing fast, and since cannabinoids are plant-based ingredients—whose applications span everything from beverages to skincare—it requires a lot of lab work, with sterilization after every development batch. Thus these cannabis companies have become a fast-growing sector of Tomy autoclave customers. 

This list is hardly exhaustive. We see autoclaves used in veterinary settings. We’ve even read about their use in creating pre-impregnated carbon-fiber components! 

Do you have a surprising or unusual usage for your autoclave? Write us and let us know; we may feature you in a future blog!

How to Sterilize and Dispose Plastic Agar Plates and Petri Dishes

How to Sterilize and Dispose Plastic Agar Plates and Petri Dishes

A Messy Affair: Sterilizing and Disposing Used Agar and Petri Dishes

Agar plates, otherwise known as Petri dishes, serve as an integral and irreplaceable part of microbiological research, particularly in their functional and utilitarian role in culturing bacteria, fungi, and other microorganisms.

Though relatively easy to prepare and requiring a minimal amount of equipment to culture, clean-up and disposal can be a messy affair, requiring the user to undertake procedures to sterilize and minimize the risk of potentially harmful microorganisms contaminating both inside and outside the laboratory environment.

Standard protocol requires the use of autoclaves to sterilize agar plates, as only high heat and pressure can effectively kill the full range of microorganisms, which can persist even under unusually harsh conditions. Alternative agar plate sterilization methods not requiring the use of autoclave sterilizers, such as microwave ovens or caustic chemicals have been recommended in place of using autoclaves. However, these methods have been proven ineffective due to the resistance of certain microorganisms.

The method in which agar plates are placed in biowaste/biohazardous waste bags and sterilized in autoclaves has become the standard protocol at many laboratories. However, this method comes with downsides, as liquified agar mixed with biomaterial can easily leak and cause a large mess, within the laboratory or on its way to waste disposal areas and beyond.
When paired with the correct autoclaving accessories, the autoclave sterilization method for plastic agar plates/Petri dishes can be both effective in deactivating harmful microorganisms and preventing a large mess.

Please find below the following plastic petri-dish agar plate sterilization and disposal method using an autoclave sterilizer, broken down into a few easy steps.

  1. Collect Used Plates

Collect used petri dishes / culture plates with agar.  Cultured agar plates / petri dishes should be left as is with agar and covered to prevent the spread of microorganisms and reduce the risk of contamination.

2. Load Agar Plates / Petri Dishes

Load used culture plates in the plastic petri dish / agar plate sterilization basket, removing covers and placing them aside before loading the agar-filled portion in the specialized perforated basket. Place dish / plate covers on top of the agar-filled portions at the end.

3. Set Up Bucket and Stand

Set up the stand inside the specialized solid bucket and fill with water to prevent melted media from solidifying inside the bucket. The stand will be used to place the specialized perforated basket on top of the water to allow the melted media to fall through. Fill water to about half of the height of the stand.

4. Load Bucket with Stand

Place the water filled bucket inside of the autoclave. Next, place the perforated basket with disassembled plastic petri dishes / agar plates, resting the basket on the stand.

5. Run Cycle

Close autoclave and run a normal sterilization cycle for at least 20 minutes. Please note that the sterilization time differs with the amount of plastic petri dishes / agar plates.

6. Unload

After sterilization cycle is complete and the autoclave temperature has cooled down to a safe level, remove perforated basket. Even though the temperature is registered at a safe level, please be mindful of hot steam, liquids, and media.

7. The Chunk

Note that the plastic petri dishes / culture plates and lids have melted and re-forged into a large chunk.  Some of the agar material has been trapped / fused into the plastic, and though it should be sterile, avoid touching parts where agar is exposed to prevent a mess.  Most of the agar has melted and mixed with the water inside the bucket.

8. Throw Away- No Mess!

Dispose the plastic chunk and pour water into a biohazardous liquid receptacle or a drain where it can be safely disposed and eventually processed.  Safe, easy and no mess!


A Means to a Mess

​As you can see, petri dish sterilization can be done safely and easily with little mess, drastically reducing the risk of contamination.

If you are interested in the aforementioned agar sterilization accessories or the compatible TOMY SX-Series autoclaves, please fill out a contact form and one of our sales representatives will get back to you shortly.

Tomy SX-Series Autoclave Sterilizer

Saves You Lots

Fast and Cost-Effective Autoclave Scale-Up for Antibody Production Research

Fast and Cost-Effective Autoclave Scale-Up for Antibody Production Research

Sourcing autoclaves to sterilize small bioreactors and fermentors can be challenging due to the configuration of and cost of most autoclaves

Sourcing autoclaves for bioreactor or fermentor sterilization can be challenging due to complex logistics and funding limitations, however, top-loading autoclaves’ can be an ideal solution for quickly increasing a research operation’s sterilization capacity.

The Promise of Recombinant Antibody Treatment

As a promising therapy against coronavirus and other viruses, there has been an increased focus on monoclonal antibody (mAbs)-based treatments and possibly preventative therapies.  This in turn has raised the demand for equipment necessary for antibody production research, as well as preemptively increasing demand for equipment used in full-scale production.

Though there are a plethora of antibody cloning methods, whether the host of choice is bacteria, yeast, or mammalian cells, etc., the preferred methods for scalability will involve the use of bioreactors or fermentors to maximize production levels and increase efficiency.  Anyone who has been involved in antibody cloning operations will also know that proper bioreactor and fermentor sterilization is key to preventing contamination and maintaining production levels.

Challenges in Increasing Sterilization Capacity

Autoclaving is the preferred method for bioreactor and fermentor sterilization due to the ability to effectively sterilize the entire contraption under highly pressurized steam.  However, increasing an operation’s autoclaving capacity in a short amount of time is not an easy task, both in terms of logistics and funding.  This is often due to the fact that autoclaves tend to be large and expensive pieces of equipment, which not coincidentally are also difficult and time-consuming to source, install, and maintain.  

Many laboratories, which are still in the early to intermediate research stage and unclear on the promise of mAbs-based therapeutic products may not be ready to make large-scale capital investments in industrial-scale autoclaves.  Due to the awkward configuration of most industrial autoclaves, those that are large enough to accommodate small to medium-size bioreactors and fermenters would require investments of tens of thousands of dollars, even to meet marginal throughput.  Fortunately, there are autoclaves that are designed to effectively accommodate smaller bioreactors and fermentors, while being inexpensive, compact, and easy to install.

Top-loading autoclaves and the vertical configuration of the chamber allows for efficient research-scale bioreactor and fermentor sterilization

Top-loading autoclaves' vertically aligned chambers are ideal for sterilizing bioreactors and fermentors

Top-loading autoclaves’ vertically-aligned chamber configuration provides the perfect solution for effectively and affordably scaling a bioreactor and fermentor sterilization operation.

Top-Loading Autoclaves for Bioreactors / Fermentor Sterilization

Top-loading type autoclaves are ideal for sterilizing bioreactors and fermentors typically found in research laboratories, due to the design, utility, and affordability of these types of autoclaves. 

Laboratories that have immediate demand to scale their operation may find the following features useful:




  • The vertical configuration of top-loading autoclaves makes loading/unloading of bioreactors and fermentors easy (and maintain vertical alignment during loading and sterilization cycle), especially compared to smaller front-loading autoclaves. Using a tall loading basket allows for easy handling of heavy bioreactor/fermentor cylinders, especially when the device is hot after a sterilization cycle.
  • The vertical configuration allows for bioreactors and fermentors to be sterilized with liquid culture media inside the cylinder. When used with a tall basket, liquids can be caught and prevented from entering the chamber water.
  • Top-loading autoclaves have a relatively small footprint for their capacity. TOMY SX-Series autoclaves have the smallest known footprint to chamber size ratio among top-loading autoclaves.
  • TOMY top-loading autoclaves require no installation (steam or exhaust connections) and simply need to be plugged in and filled with water.



  • Standard front-loading autoclaves large enough to accommodate bioreactors and fermenters are prohibitively expensive for smaller organizations and highly ineffective (in terms of price to loading capacity) for all organizations. Relatively speaking, top-loading autoclaves, such as TOMY SX-Series autoclaves are very affordable in high loading capacity for sterilization of bioreactors and fermenters.
  • Due to the simplicity of design, reliability, and low maintenance needs, top-loading autoclaves are more affordable in terms of long-term upkeep costs.


As illustrated, top-loading autoclaves can be both an effective and efficient means in bioreactor and fermentor sterilization, as well as quickly and cost-effectively scale-up antibody production research operations.

For pricing and questions concerning TOMY SX-Series autoclaves and compatibility of bioreactor/fermentor models, please use our contact form, email, or call us at 858-800-3900.

Tomy SX-Series Autoclave Sterilizer

Saves You Lots


Disclaimer: TOMY autoclaves for research use only.  Information contained in this blog entry is not meant to substitute proper research, execution, and maintenance of laboratory practices.  Please check the most up-to-date information on authoritative sources and adhere to applicable federal, state, and local regulations.

Autoclaves for Start-Ups

Autoclaves for Start-Ups

The cost of an autoclave for a start-up is considerable, especially when taking into account long-term costs

When selecting an autoclave at a start-up lab, in addition to functionality one of the most important considerations is costs, both in the short and long-term.

The Start-Up Autoclave: What You’re Up Against

Let me start by describing a scenario that may sound familiar to you: You’re working at a biotech startup or small laboratory. You’ve been tasked with buying basic lab equipment. You’re looking at autoclaves and you’re not impressed with the options. Too big. Too small. Not enough throughput. Too much of a pain to maintain and deal with repairs. Too expensive…and way too expensive.

If any of this sounds familiar to you, I’ll be talking about how to find the ideal autoclave for startups and small labs. I will cover features to look for, as well as how to save money and time in the short and long term, which are both extremely important for startups.

The Checklist

As you embark on your autoclave search, you probably have many criteria, but it basically boils down to an autoclave that is:

  • Compact
  • Large capacity
  • Accommodates large items (large bottles, bioreactors, etc.)
  • Easy to install
  • Easy to maintain
  • Won’t break the bank with maintenance, repairs, and other headaches

Let’s look at the options below and see how they hold up.


Option: The Bench-Top Autoclave

After you have your checklist, you look at your options- the first one that you’ll probably come across is the benchtop autoclave.

These look like a large microwave oven that sits on the benchtop with the door on the front. Compact and convenient, right? When you take a closer look, you’ll see that they come with many disadvantages.

For one, they don’t fit much inside. When you open one up, you’ll see that there’s a box-shaped area sitting in a sideways-facing cylinder, which creates a lot of unused areas that waste space from the start.

On top of that, the small clearance means that you’re not going to fit much in there. If you need to autoclave large flasks, you’ll be lucky to fit even one, and if you have a bioreactor or fermenter, good luck getting that thing in there.

The second major disadvantage is that they’re a benchtop autoclave. They sit, taking up valuable workspace or space that can be used for other valuable equipment. If space is already at a premium, why use this space if you have other options?

Conclusion: It’s best to look past front-loading bench-top autoclaves, because:

1) They’re too small for your equipment and limit throughput

2) They take up badly needed space


Option: The Large Front-Loading Autoclave

Another option is the large, front-loading autoclave. This is like the giant cousin of the benchtop autoclave. They basically take the same front-loading format, but instead of putting it on the benchtop, it’s designed to stand on the floor in some unused corner of your lab.

Some might say that this saves benchtop space, so it’s good,  RIGHT?  Well, this comes with the same disadvantages as benchtop autoclaves with its sideways-facing cylinder. These also have the box built inside the chamber, so you’re wasting idle space and you’re not getting much in there.

Doing some basic math, you’ll find that a 100L capacity autoclave, with a square box built into a sideway cylindrical chamber only, has at most 70 liters of autoclaving space, meaning that you’re wasting 30% right off of the bat.

You’ll also find that a cube is an awkward space to place mostly round items, meaning you’re wasting more, especially if you can’t effectively stack these items. On top of it all, you’ve got a bunch of idle, unused space below the autoclave. So in the end, even though you’ve moved the autoclave off of the bench, it’s taking up a lot of space that won’t be used for autoclaving.

Finally, if you’ve ever looked into a large, freestanding front-loading autoclave, you’ll know that they come with a hefty sticker price.  There’s a lot of other costs associated with these large autoclaves as well, especially maintenance and repair costs.

Conclusion: Large front-loading autoclaves have the same problems as small bench-top autoclaves, including:

1) The sideways-facing cylinder is an ineffective use of space

2) Cube-spaced don’t accommodate lab media, which are mostly round

3) They’re huge and expensive (and a major headache to deal with)


Option: Top-Loading Autoclaves

So, we’ve covered benchtop and floor-standing front-loaders and we’ve found that they’re not that efficient in their use of space. If you’ve looked at prices, you’ll also find that they’re not all that cheap either, even considering that they’re not able to handle much. I’d like to now turn our attention to top-loading autoclaves.

So, to quickly summarize top-loading autoclaves, they are, as the name implies, completely different from front-loading autoclaves in their design. Take, for example, the TOMY SX-Series autoclaves.

In top-loading autoclaves, the cylinder is oriented not horizontally, but vertically. This confers many advantages.

For one, it won’t take up any space on your bench and hardly any space on the floor. This autoclave here takes up less than 3 square feet and can be placed anywhere it has a source of electricity. No plumbing or exhaust installations are involved.

Another thing that’s great about top-loading autoclaves is that you’re using the full cylinder to sterilize- because it’s vertical, there’s no need to have a box built into it or have trays that slide in, you’re really using the cylinder in its entirety.

Conclusion: Top-loading autoclaves confer many advantages for small start-up labs.

  1. They’re compact and won’t take up benchtop space
  2. The vertically oriented cylinder is a more efficient use of space
  3. They’re easy to install and can be placed virtually anywhere in the lab

There are a lot more advantages to top-loading autoclaves, let’s take a deeper dive below.


Top-Loading Autoclaves’ Loading System

If you’re new to top-loading autoclaves and wondering how to load items, they use a clever system of baskets and buckets to pre-load and place items into the chamber. Baskets and buckets come in various sizes and configurations for different media including small items such as glassware, liquid media, and large items such as bioreactors or fermenters.

For small to medium-size items, the TOMY SX-Series comes with stackable baskets.  The SX-Series can stack up to 3 of these baskets inside, so with each of these baskets fully loaded, you’re able to pack quite a bit in each cycle. TOMY autoclaves can also accommodate up to 2 stainless buckets for autoclaving liquid media or slightly larger items like 5-liter bottles. There is also a tall solid-bottom basket that takes up the chamber in its entirety to autoclave the largest items, or use for sterilizing waste.

TOMY autoclaves are extremely handy for autoclaving large items such as fermentors or bioreactors because you can load and autoclave the entire cylinder using a tall solid-bottom basket.

With this one small autoclave, you can take care of a range of items, eliminating the need for an industrial-size autoclave that’s going to waste your operation’s valuable time and money.


Top-Loading Autoclaves’ Low Maintenance Costs

If you’re working at a biotech startup or small lab, you’ll know that funds are difficult to come by, so you’ll want to avoid spending on maintenance and repairs as much as possible. To put it another way, you’ll want to avoid purchasing an autoclave that’s going to cost you a lot down the road.

The most common type of autoclave maintenance is lid gasket replacement. Lid gasket replacement costs can be deceptively high, sometimes up to thousands of dollars a year. Because of their design, front-loading autoclaves use a very thin lid gasket that can require changing in as little as one month. At hundreds apiece, in a matter of a few years, your spending on these rubber bands will surpass the cost of the actual autoclave. Your investors will not be happy, and you will not be happy either if your autoclave is keeping your operation from turning a profit.

The lid gasket on TOMY Autoclaves is completely different. It requires changing once every 1,000 operating hours, which works out to be once every 1 – 3 years. Starting at under $600 a piece, these gaskets alone will keep maintenance costs as low as a couple of hundred dollars (USD) a year, compared to thousands, helping you to keep your operation’s balance sheets healthy and in the black.


Top-Loading Autoclaves Repair Costs

If you’ve ever dealt with an autoclave breaking down, you’ll know that repairs can leave a huge dent in your operation’s balance sheet, easily in the thousands each time. You probably also know that if something happens once, it’s likely to happen several times. To look at things from a larger perspective, it’s not only the monetary cost of the repair itself, but the cost of your entire operation grinding to a screeching halt.

If you have the option, you’ll probably want to avoid this altogether. The simplicity of design and few moving parts, combined with the sturdy gasket, will keep your TOMY autoclave from breaking down and bogging down your operation and balance sheets.

TOMY autoclaves are still manufactured in Japan, where the SX-Series’ lifetime exceeds 15 years, which is quite remarkable because it means that most of the first generation models are still up and running. By investing in a TOMY top-loading autoclave and regularly replacing the gasket, your autoclave will give you more than plenty of time to grow your small startup into a thriving multinational.

For a deeper look at both short- and long-term costs associated with autoclaves, check out the post “How Much Does an Autoclave Really Cost?



In summary, if you’re a biotech startup or small lab, you’re looking to not only get your operation off the ground but to keep it running smoothly and at low cost until things really take off.

You’ll want to find that autoclave that’s compact and won’t take up tons of valuable space and can take care of everything, from small glassware to liquid media to bioreactors and other large items.

You’ll also want an autoclave that’s easy to install, easy to maintain, and won’t break the bank with gasket changes and repairs.

If you can take care of all the above, you and your hard-working co-workers are one step closer to cashing out on those stock options and relaxing on the beach on your private island in the South Pacific.

If you’d like to know more about how TOMY autoclaves can save your startup lots of money and time, please use our contact form, email, or call us at 858-800-3900.

Thank you for visiting and I look forward to assisting you with questions that you may have!

Tomy SX-Series Autoclave Sterilizer

Saves You Lots

How Much Does an Autoclave Really Cost? (Hint: The Purchase Price Is Just Part of It)

How Much Does an Autoclave Really Cost? (Hint: The Purchase Price Is Just Part of It)

In addition to the original purchase price, long-term maintenance and repairs can
add a significant amount to the cost of an autoclave.

Autoclave Costs: Much More Than You Think

Shopping for an autoclave?  Chances are that this is your first time or you’re not satisfied with the autoclave you have and the price you paid for it.  

One of the largest concerns is the cost- if you’ve dealt with other equipment you’ll know that not only initial purchase costs but that ongoing maintenance and repair costs also need to be factored in the equation.   Whether it’s utility costs, cost of replacing door gaskets, and worst of all, costs of repairing that dud of an autoclave that broke way too soon, you’ll be paying more than you expected and in the process, regret the decision that you made on the purchase.

I’ll be covering initial purchase costs, long-term upkeep, and maintenance costs, as well as other factors that ratchet up the costs so that you can know what to expect financially when purchasing an autoclave.

Initial purchase cost

Chances are also that you’re overwhelmed with the tremendous number of choices for autoclaves and you don’t know where to start.  You may have started crawling the web and logging different models and their costs, and choosing one that meets your budget.

If this is your approach and you’re searching first for autoclaves by cost, stop right now, because you’re wasting valuable time, and may end up with an autoclave that won’t meet your needs!

Before starting any search, know what you’re looking for in terms of size, configuration, and features.

Autoclave Size

First of all, you’ll need to know what you’ll be autoclaving and what kind of capacity you’ll need.  Though you may sometimes only autoclave a few pieces of glassware or utensils, other times you’ll need to autoclave many items, and thus, you should think about the maximum amount that you’ll need.  

You’ll then need to figure out the dimensions of these items and how much total space that all the items put together will require.  This is tricky, because of unique shapes, and how different items will fit together.  

A good rule of thumb is to think of the largest item that you’ll be autoclaving and how many of these you’ll need on any given day.  Though height, width, and depth (or diameter) will all be important to take into account, overall, the vertical clearance is likely to be the largest hurdle and thus the most important factor to consider, which differs greatly depending on whether your autoclave is front-loading or top-loading (see the section below).  

No matter what other factors you take into account, make sure to accommodate your largest items and you’ll avoid getting an autoclave that is too small for your needs.

Autoclave Configuration

People often find that they’ll need more space than what a typical microwave-sized benchtop autoclave offers, but aren’t able to invest in a large autoclave that you’ll find in a university lab.

In terms of bang-for-your-buck, this is where top-loading or vertical autoclaves come in handy.  Though autoclave chambers are cylindrical in both front-loading and top-loading autoclaves, in the latter the chamber sits vertically and accommodates stackable baskets.  With these, you can fit a large amount of media inside, including large items like 2-liter bottles or flasks and bioreactors/fermentors.  

If you’re autoclaving tall and large items like bioreactors or fermentors, it is important to know that top-loading autoclaves are the most affordable for accommodating large items, due to the compatibility with the vertically-oriented chamber.  So if you’re looking to do more than just a few vials or bottles, a top-loading type may be your best choice of an autoclave.

Special Features

When looking for an autoclave you’ll also need to consider special features.  One of the main additional features is the vacuum feature.  Whether you’ll need this or not solely depends on what you’ll be autoclaving.  

If you’re autoclaving standard glassware, liquids, or smooth-surfaced items that don’t have hard-to-reach places or air pockets, a standard gravity autoclave will do.  

If you’re autoclaving fabrics, other porous items, or items inside sterile envelopes, you’ll need the vacuum function.  For more information on this please see our vlog on types of autoclaves.

Purchase Cost

Once you know the size, configuration, and necessary special features on your autoclave, you’ll finally be ready to start looking at prices.

As you make your way through, you’ll notice that there’s a pretty large range of prices, and not much consistency in value, ie. what you get for the price you pay.  

I suspect that the reason behind these outrageous prices is that manufacturers know that they can overcharge because people are willing to pay high prices on equipment that they’re familiar with and don’t bother to look outside of what they know.

Don’t ask “how high?” when these outdated manufacturers tell you to jump for their high prices, especially when this equipment doesn’t cut it in terms of capacity and quality.  Would you pay the price of a luxury car for an outdated, underperforming car that your father drove 30 years ago?  If the answer is “no,” then don’t overpay for an outdated autoclave either!

The Price Rule

In the new autoclave market, the basic rule is that if it’s priced above $10,000 and doesn’t have at least a 40L chamber capacity, then don’t even consider it!  If you need special features like a vacuum function, that will add several thousand to the price, but if you’re looking for a standard gravity autoclave, if you’re getting less than a 40-liter capacity, don’t pay over $10,000; it’s pretty much priced way higher than it should be.

Also, consider the configuration– for the same chamber volume,  you’ll fit way more inside a top-loading autoclave, because you’re using the whole chamber, not just the box space built in a sideways cylinder on a front-loading autoclave.

Maintenance Costs

If you’ve ever been in a lab with an autoclave, you’ll know that the costs don’t end once you’ve purchased it.  This includes both maintenance and repair costs, which can be significantly different depending on the autoclave type.

The most common type of autoclave maintenance is a lid gasket change.  This is something that can’t be avoided because the proper operating temperature and pressure depend on a lid gasket in good working condition, free of cracks and deterioration.  Your autoclave’s life also literally depends on a good lid gasket, because steam leaks can damage an autoclave’s electronics and render it useless in a short amount of time if not changed.

The Gasket Cost

Lid gasket replacement costs differ wildly, depending on the material and how often they require changing.  Certain lid gaskets can require changing in as little as one month.  Your cost is basically the lid gasket cost multiplied by the number of times it needs to be changed over the lifetime of your autoclave.  Usually, at around a couple hundred apiece, this can drive your autoclave’s maintenance costs up to thousands of dollars per year!

TOMY SX-Series autoclave lid gaskets are quite unusual, being much thicker and sturdier in build than the flimsy, thin rubber band-like lid gaskets found on many front-loading autoclaves, which are the main culprit in the astronomical maintenance costs of many front-loading autoclaves.  TOMY SX-Series lid gaskets require changing once every 1,000 operating hours, which works out to be once every 1 – 3 years.  Starting at around $550 a piece, compared to the total price for changing the gasket every month on other types of autoclaves, the TOMY lid gasket alone will save you thousands of dollars in the long run.

So, always remember to factor gasket replacements in your maintenance costs, and choose an autoclave that will keep this to a minimum, ideally a couple hundred a year for moderate use and no more than $600 a year for heavy use.

Repair Costs

Autoclaves breaking down and the associated repair costs can be extremely costly.  Not only is this devastating to your overall budget, with so many things to do around the lab it’s simply one of the last things that you will want to deal with.  Because of the numerous mechanisms in certain types of autoclaves and the tremendous heat and pressure that they operate under, autoclave break-downs are quite common.  Some autoclaves, especially large core facility autoclaves seem to be broken as much as they working.

If you have ever dealt with autoclaves being broken you know that it is quite expensive.  It may cost a couple of hundred dollars or more per hour to have a specialist come to diagnose and work on your autoclave.  There are also part costs as well- burnt out heaters and electronics can cost hundreds or even thousands of dollars to replace.  This can easily add up to several thousand every time your autoclave breaks down.  Just multiply the thousands of dollars a breakdown can cost by the frequency that they break down and you’ll get the long-term cost of repairing your autoclave, which can easily exceed the original purchase price.

Saving on Repair Costs

It’s not only the monetary cost of the repair itself, but the time lost due to the breakdown can have an even more devastating effect on your operation.  Basically, to reduce this cost, you’ll want to go with an autoclave that has a reputation to last and is known for quality and durability.

TOMY SX-Series autoclaves are quite simple in their design with few moving mechanical parts and are built with a sturdy gasket to keep your autoclave running for years.  In Japan, where they’re manufactured, the average lifetime exceeds 15 years, which is quite remarkable because it means that most of the first generation models are still up and running.  By making sure that you’re regularly changing your gasket, you can prevent problems associated with leaking heat and steam and ensure that you’ll be saving money on repairs.  Basically, a small investment in maintenance will go a long way in saving you lots in the future.


In summary, the cost of your autoclave is the aggregate cost of the purchase price, and costs to maintain and repair your autoclave.  By taking the time to know what features you need, you can easily find a great autoclave that meets these needs at a reasonable cost that will also save you lots on repair and maintenance in the future.

If you’d like to know more about how TOMY autoclaves can save you lots, please use our contact form, email, or call us at 858-800-3900.

Thank you for visiting and I look forward to assisting you with any questions that you may have!

Tomy SX-Series Autoclave Sterilizer

Saves You Lots