What is an Autoclave and How to Use It?

What is an autoclave and how to use it?

Table of Contents


There are spheres where you need to sterilize objects for use or disposal. But how to sterilize these objects? In this article, you will learn what an autoclave is, its pros & cons, how and where it is used.

What is an autoclave?

Anautoclave (also called asteam sterilizer) is a machine that uses pressurized steam to sterilize equipment, waste, etc. In this process, such microorganisms as bacteria and spores are killed. Sterilization using an autoclave is one of the most effective and affordable methods if you need to sterilize liquids and solids of various sizes and shapes.

PROS & CONS of using an autoclave

PROS & CONS of using an autoclave

As most things, autoclaves have their advantages and disadvantages.


  • non-toxic;
  • cost-effective;
  • time-effective (especially compared to using other ways of sterilization);
  • excellent penetration level of steam;
  • excellent microbicidal and sporicidal effect (steam kills microbes and spores).


  • the list of objects that can be sterilized is limited (for example, you can't autoclave corrosive, explosive, reactive objects, etc.). See the “Things that you CAN and CAN'T autoclavesection.

How does an autoclave work?

How does an autoclave work?

Essentially, an autoclave is a steel vessel through which steam is circulated for object sterilization. As a rule, an autoclave has a cylindrical chamber where you place an object.

The object that needs to be sterilized is known as a load. It is considered to be sterile if it has undergone a full sterilization cycle.

The working principle of an autoclave is pretty simple. There are 3 phases:

1. Purge phase

The door of an autoclave is locked so that a sealed chamber is formed. The air within this chamber is replaced by steam.

2. Sterilization phase

The exhaust valve is closed and the interior temperature & pressure increase so the object (load) can be sterilized. The desired temperature is maintained until the desired time is reached.

3. Exhaust phase

When this cycle is complete, the steam is exhausted and the load can be removed.

Things that you CAN and CAN'T autoclave

You can't autoclave anything you want. Let's figure out what is safe to autoclave and what is not.

You CAN autoclave the following:

  • stainless steel;
  • autoclavable glass;
  • autoclavable plastic;
  • autoclavable waste;
  • bedding;
  • and more.

Now let's list the things that you can't put in the autoclave.

You CAN'T autoclave the materials that are:

  • flammable (e.g. items that contain solvents);
  • reactive (e.g. chlorine-based substances);
  • corrosive (e.g. bleach);
  • toxic;
  • radioactive;
  • explosive;
  • non-autoclavable plastic, waste;
  • sealed containers;
  • the list goes on.

Always make sure you know whether the piece of equipment, instrument, or any other thing you want to sterilize is autoclavable or not.

How to use an autoclave for sterilization? (a step-by-step guide)

Before using an autoclave, it is important to know a few simple rules:

  • always wear PPE;
  • do not touch the metal surface of the autoclave;
  • load only autoclave-safe objects;
  • always inspect the objects (for example, glass) before autoclaving (they should not be damaged, have cracks, etc.);
  • always check the autoclave for cracks, damages, or other problems before working;
  • do not overload the autoclave.

Using an autoclave to sterilize objects is easy if you follow the steps below.

1. Put on your personal protective equipment.

How to use an autoclave for sterilization?

As autoclaves use steam to kill harmful bacteria, you must protect yourself. To prevent burns and scalds, wear:

2. Prepare the load.

Steam needs a way to penetrate into the object (also known as a load). Avoid air pockets that can be formed in the load. They may get in the way of proper sterilization.

On a glass bottle that has a lid, loosen the lid so the steam can penetrate inside.

If you want to autoclave glassware without lids (e.g. beakers), wrap the top with aluminum foil. You can also apply autoclave tape over the foil.

How to use an autoclave for sterilization?

The glassware containing liquid should be placed in a spill containment tray that is autoclavable.

How to use an autoclave for sterilization?

An autoclavable waste bag (or red bag) should not be tied, shut, or otherwise sealed. Note that there should be a small opening on the top of the bag so the steam can penetrate and escape.

How to use an autoclave for sterilization?

3. Prepare the autoclave.

Make sure that the drain at the bottom doesn't have any debris. Clean it if necessary.

Check if there any bulges/cracks on the door gasket. For effective sterilization, the gasket should be pliable and smooth as well.

If there are any problems with your autoclave, contact the expert to fix them. Never use the autoclave if it doesn't function properly.

If everything's alright, turn on your autoclave and wait until sufficient temperature and pressure are reached.

4. Load the autoclave.

Open the door of the autoclave and put the load inside.

How to use an autoclave for sterilization?

How to use an autoclave for sterilization?

Note that the load should not touch the bottom floor or the side walls of your autoclave.

If there is a metal wire rack shelf in your autoclave, the load should be placed so that it is accessible from the door of the autoclave.

The chamber drain should not be covered so that steam can flow freely to it.

5. When the objects are loaded, close the autoclave door.

How to use an autoclave for sterilization?

If you have an autoclave with a hinged door, close the door fully. Engage the locking pins and turn the locking mechanism until it stops moving.

How to use an autoclave for sterilization?

6. Select the cycle suitable for the load inside the chamber.

How to use an autoclave for sterilization?

It is an important step as you need to select the right cycle. Otherwise, you won't achieve the results you want. To make the right choice, read the user's guide that comes with the autoclave. For example, if you are sterilizing a waste in a red bag, select the gravity cycle. Once the cycle has started, avoid opening the door of the autoclave. It is not safe and the autoclave can be damaged too. The duration of the sterilization process as well as the cycle type depend on various factors, including the load size, its type, etc.

In case you noticed any issues with the autoclave, abort (stop) the cycle. Then, wait until both the pressure and temperature return to safe the ranges.

7. Open the autoclave door.

How to use an autoclave for sterilization?

Slowly open the door of your autoclave if the cycle is complete and if the pressure & temperature ranges are safe.

8. Unload the autoclave.

How to use an autoclave for sterilization?

After sterilization, the load (especially if it is a liquid) can be extremely hot. Avoid agitating liquid containers or removing caps while unloading the autoclave.

The load should be placed in a specially designated area. Indicate that it is a place with hot objects using a sign or using other ways.

9. Close the autoclave door.

How to use an autoclave for sterilization?

Uses of an autoclave

Autoclaves are used in hospitals, veterinary clinics, biology laboratories, tattoo & body piercing studios, the list goes on.

Using an autoclave is one of the best and most reliable ways to sterilize medical and laboratory equipment & instruments (for example, autoclavable pipettes, autoclavable racks) to be reused. Lab equipment can be sterilized between uses in order to prevent cross-contamination of cultures.

Note that for the sterilization of the equipment and plasticware/glassware with labels on them, you should make sure that you use autoclave-resistant labels.

Medical waste can be hazardous. Before disposal into municipal waste facilities or landfills, it is necessary to sterilize such waste and autoclaves can help with this task.


After reading this article, you know the answer to the question “What is an autoclave used for?”, understand how an autoclave works, its pros and cons. In addition, now you can use an autoclave for sterilization. Just follow all the safety rules and the manufacturer's instructions that come with the autoclave.

On Mega Depot, you can choose from an array of high-quality autoclaves as well as steam sterilizers. There is a wide range of products from small to large capacity autoclaves, choose the best option for your application!

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