Last Updated on October 27, 2023


Common Autoclave issuesA steam sterilizer, a.k.a. autoclave, is a tool that your lab or production facility relies on all the time. But like any device, an autoclave can sometimes have issues that degrade its performance, or render it unusable, either temporarily or permanently. Obviously, autoclave downtime costs you time and money, not to mention frustration.

This article will help. Here, we’ll walk you through the most common autoclave issues. We’ll teach you how to easily troubleshoot them. Importantly, we’ll show you how to prevent many of them. And we’ll let you know how to recognize when that old autoclave is beyond repair and must be replaced.

Seal of approval

A quick recap of Autoclave 101: The device performs its sterilization magic by combining heat, pressure, and time. (We wrote about this, which you may want to check out.) It heats water beyond the boiling point, reaching a typical temperature of 121°C, by trapping it in an airtight chamber, where the water turns to high-pressure steam. In due time (typically 20 minutes), this high-pressure steam pushes its way into all the voids in the medium you intend to sterilize, killing any exposed bacteria, fungi, or viruses.

The key word in the above paragraph is “airtight.” To use the autoclave, you load it with your media or instruments to sterilize, add water, seal it shut, and power it up. Sealing is the important part here. Every autoclave has a door or lid, and every door or lid has a gasket whose job is to provide a perfect, airtight seal.

If that gasket doesn’t form a proper seal, you’ll have issues. This is the most common problem we see. Without a perfect seal, the autoclave won’t be able to contain the steam and generate the proper pressure needed for sterilization. Even worse, this can be hazardous: you don’t want contaminated steam leaking into your workspace. And you certainly don’t want to risk getting burned by hot steam.

If you see leaking steam, that’s a surefire clue. And your autoclave will report an error code, too, showing insufficient pressure.


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Stock answer

Gaskets are wear items. They don’t last forever. (Shameless plug: Most autoclave gaskets last a few months, whereas Tomy autoclaves are much thicker and more robust, so they typically last from one to three years.) So always keep at least one other in stock and handy.

Replacing a gasket is a DIY project, requiring only simple tools and about 15 minutes of your time. You can be up and running again quickly.

Level headed

This might sound silly, but we see it all the time: If your autoclave doesn’t want to start, check the water level.
This problem is embarrassingly common. If you don’t have enough water, you need to add some.

Sometimes, however, this issue is trickier than it might appear. Depending on where you live, your local water may not be hard enough to trigger the autoclave’s sensor. Or (again, depending on where you live), your water may be too hard, to the point where it causes corrosion on the sensor.

Similarly, it’s possible to over-fill the autoclave; you don’t want, say, your sterilizing liquid spilling into your glassware. If you add too much, simply drain off the excess.



What you put in your autoclave contributes to the risk of problems. Ordinary glassware, for example, is usually issue-free. But if you’re dealing with liquids or any substance that could cause contamination, be careful. You don’t want it to boil over. And never tighten the cap of any item that you autoclave; always allow a gap for steam to escape.

Smart shutdown

If you don’t plan to use your autoclave for an extended period of time, consult its user manual and follow the proper shutdown procedure. If you, say, leave liquid or culture media inside, things may start to grow in it. That can cause more than just an unpleasant smell; it could also cause rust.

Stop problems before they start

You’ve probably figured out by now that preventative maintenance is key to avoiding downtime. For example, if you have hard water in your area, you’ll need to de-scale your autoclave to prevent damage. We can recommend de-scaling products; contact us to learn more.

And always use genuine manufacturer parts. We’ve seen old, obsolete autoclaves that have been jury-rigged with off-brand parts to try and keep them going. That’s not just ill-advised; it can be dangerous. If you use, say, a pressure valve that happens to be off-spec, the results could prove catastrophic. Don’t go there.

When—and how—to get help

Keep your owner’s manual handy. It will help you understand and react to any error codes that appear on your autoclave’s display. You can also visit the manufacturer’s website to look up issues.

Many people prefer phone support. If this describes you, make sure the autoclave you buy includes it; that’s part of what you purchase when you choose that brand. (Tomy autoclaves, incidentally, come with phone support, with calls typically returned by a certified technician in just an hour.)

When it’s time to replace

While proper maintenance will maximize their lives, autoclaves don’t last forever. Here are the biggest indicators that it’s time to replace that old unit:

    • It’s down more than it’s up.
      If you’re constantly calling for tech support, and continually racking up big repair bills, that autoclave likely isn’t worth fixing anymore. Stop throwing parts at it; stop throwing good money after bad.
    • You can’t get parts.
      We’d mentioned genuine manufacturer parts, above. If you can’t get them anymore, your autoclave is obsolete. Time to shop for a replacement.
    • The internal chamber has been compromised
      The internal chamber of an autoclave is the part that contains its high pressure; that’s why it’s typically cylindrical, to be as strong as it can. If it gets dented or otherwise deformed, it’s useless.

A good place to start

If it’s time to consider a new autoclave, consider a Tomy. We invite you to learn more about their many advantages and many uses.



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