Last Updated on July 22, 2022



A clean and well-maintained autoclave is central to keeping a sterile,
well-functioning (and happy) laboratory environment!

Operating instructions and preventative maintenance

Though autoclaves, sometimes referred to as steam sterilizers are pieces of equipment designed to disinfect and sterilize laboratory media (glassware, plastic ware, etc.) as well as biohazard waste, they must be maintained and used in a way that allows them to properly function and is suitable for long-term use. This is especially true of steam sterilizers or gravity autoclaves, which heat water to extremely high temperatures up to 135° C and subject media (and the autoclave sterilizer itself) to high temperature and pressure. Because of these volatile conditions under which autoclave sterilizers operate, maintenance includes using the proper type of water with your autoclave, autoclaving in a way that prevents media from spilling into your autoclave, and regularly changing the gaskets, all of which maximize sterilization ability and extend the lifetime of your autoclave.



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It’s something in the water (or the water itself)


One priority when operating autoclave sterilizers that use steam is to use the proper type of water. The most plentiful, cheap, and easy-to-access source of water is tap water, however, the high mineral content of tap water in many areas can cause problems for your machine. In many parts of the United States, tap water contains a high mineral content including lime, which can calcify and leave a residue on the autoclave heater and inside the chamber, leading to permanent and irreversible damage, especially to the heating unit, which is central to the sound operation of the autoclave. For water mineral content (hardness/alkalinity) by area in the United States, please visit this page.

To prevent the problems caused by high mineral content water, autoclave sterilizers that use steam should be operated with DI water, which stands for De-Ionized water and is also referred to as Demineralized Water. This type of water can either be purchased or created by de-ionizing tap water using special equipment found in most laboratories. Though they are often confused with one another and sometimes used interchangeably, please note that DI water is not the same as Distilled Water, as they are created using different processes and can change the outcome of experiments depending. More information on the differences can be found here.

With Tomy SX-Series autoclaves, DI water with a small amount of tap water should be used, as the water sensor works by detecting ions in the water, as opposed to water itself. Please fill the autoclave chamber with enough DI water to cover the heater (up to the bottom plate inside the chamber) and submerge the water level sensor (small metal knob that protrudes from the inside of the autoclave chamber), adding a small amount of tap water to make sure that the water sensor can detect ions. For SX-500 model autoclaves add approximately 50 mL of additional tap water to the DI water, for SX-700 model autoclaves add 100 mL of additional tap water to achieve the proper mix.

Cleanliness is next to…


The chamber should be cleaned regularly to remove solution residue that can damage your autoclave

Autoclaves should be drained and cleaned at least once a month, as another source of damage to autoclaves, especially autoclave heaters, is dirty water that sits in the autoclave chamber. At high temperatures and pressure, impurities that get into the water from the autoclaved media can stick and burn to the autoclave heater, preventing the heater from transferring heat and permanently damaging it, potentially rendering your autoclave obsolete. For Tomy SX-Series autoclaves, we can drain water in the autoclave chamber by removing the white plug and opening the drainage valve (green handle) under the machine, and draining this into a container for disposal. For biohazardous material and water disposal, especially for BSL (Bio Safety Leve1) 2 and above laboratories, please contact the Center for Disease Control or the relevant national authority for disposal instructions.

Besides draining water from the autoclave chamber, the inside of the autoclave needs to be wiped out and the heating element should be cleansed. For Tomy SX-Series Autoclaves, we can access the heating element by removing the bottom plate inside the chamber. To maintain performance and increase the longevity of your machine, we also recommend periodically removing any residue that builds up inside the chamber, especially on the heating element. For the type of cleaners that we recommend, please contact us here or via email at tomy@amuzainc.com.

Another important method for keeping your autoclave clean is to prevent autoclave media from spilling or boiling over into the water in your machine. If using open bottles of culture media or other types of solutions, please use the bucket type inserts or solid bottom tall baskets (as opposed to the standard baskets that come with your machine), to prevent solutions from overflowing into chamber water and sticking to / burning onto the heater unit.


Changing the gasket


Thick and sturdy, high-quality gaskets for the TOMY SX-Series can save your organization thousands of dollars over several years

Keeping the lid gasket, also known as an autoclave door seal, etc. in top condition is key to keeping your autoclave in proper working condition, which also ensures proper sanitization for autoclave media and laboratory safety. When autoclaving, the gasket is subject to high temperature and pressure, which can cause cracking and lead to leaks in the autoclave and will prevent the autoclave from achieving the temperature and pressure for sterilization, as well as lead to other problems and damage to your autoclave.

The recommended time for replacing the lid gasket is 3 years or fewer, especially if the autoclave is used frequently and is constantly subject to the high temperature and pressure of autoclaving. If using a Tomy SX-Series Autoclave and are due for a replacement, contact us and refer to the following Tomy autoclave lid gasket models/part numbers:


Next Steps

As laid out above, no matter what you use your autoclave sterilizer for, using the proper type of water, the proper buckets and baskets for autoclave media, and regular maintenance including changing your autoclave gaskets can both prevent damage to your autoclave and give it the proper treatment for long-term use.



If you have questions regarding any of the points outlined above or need to purchase replacement gaskets for your Tomy autoclave, please fill out a contact form and one of our sales representatives will get back to you shortly.


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