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5 common problems when operating autoclaves

Author: Site Editor     Publish Time: 2022-06-13      Origin: Site

Steam Sterilizer

Under an ideal situation, an autoclave will always work exactly as expected. However, problems do arise - and the key to solving them is knowing what to look for.

In this article, an overview of the 5 most common autoclave problems and how to identify them will be presented.

1. Sterilizer fails to reach temperature set point

Users of autoclaves are able to customize the sterilization cycle according to a number of parameters, including the sterilization temperature. If an autoclave fails to reach the specified temperature within the time it takes to run a sterilization cycle, a cycle will be aborted or an alarm will be issued.

There are several reasons why an autoclave may not reach the sterilization temperature within the given time. For instance, maybe the power of the steam generator was not turned on. Some autoclave models use an integrated steam generator, which is located underneath the autoclave chamber.

A steam generator of this type is usually connected to its own high-pressure power supply and can be turned off while the rest of the unit is still on. Should the user not realize that the power to the generator has been turned off and the rest of the sterilizer appears to be energized, it will keep the sterilizer from reaching the specified temperature.

2. Load damage

There are several problems that arise that may allow the autoclave to damage the load.

  • Melting

Autoclaves operate at really high temperatures - the kind of temperatures that could melt certain materials, like certain plastics. Thus, be sure that anything loaded into the sterilizer is safe for the autoclave.

Luckily, most laboratory equipment will state whether it is autoclave safe or lists its melting point. Melted items can damage the sterilizer, so it is essential to train autoclave users to be cautious about what they load into the unit.

  • Liquid loss

Whether in the form of evaporation or boiling, the boiling temperature of water rises as the pressure rises. If a cylinder or flask filled with water is loaded into the autoclave and run at 121°C, once the cycle is finished, the pressure will be released and the water will begin to boil.

This can create splashing and be a safety hazard; smaller vessels may even explode. To avoid this problem the best way is to run a dedicated liquid cycle that relieves the pressure in the chamber more slowly than all at once.

  • Burning sugar

In the same way that liquids have a boiling point, sugars have a caramelization point. A perfect way to avoid this problem is to simultaneously add length to the sterilization cycle and lower the temperature.

3. Improper sterilization

Poorly sterilized goods can result in contamination, growth in the medium, or failure of the bioindicator. There are many reasons why a sterilizer may fail to sterilize: improper loading, dry steam, component failure, insufficient steam, user error, etc.

One of the best ways to make sure you are sterilizing correctly is to validate the device using a Bio-Indicator (BI). To validate the autoclave, just place the BI into a typical load.

Once the load is done, remove the package and place it in a special broth and perform an incubation to observe if there is any growth. If no growth is present, it is a safe assumption that your load is compliant with that cycle formulation and should be sterilized.

4. Valve failure

Nearly every autoclave has a wastewater cooling valve that turns on and off automatically to cool the steam exiting the sterilizer prior to going down the drain. If this valve is broken, there can be problems such as a huge liquid load causing the sterilization cycle to abort or no steam in the jacket.

Many autoclaves have an additional cold water line just before the drain that has a temperature sensor on it. As this sensor detects steam, it will add a bit of water to it to cool that steam. A bad temperature sensor or a broken valve will cause water to pour out, and this will cause the autoclave to sound like a sink the whole time, or if the valve is stuck, the steam will flow down the drain.

Too much water flowing down the drain is an obvious sign that the valve is bad in the "open" position. Steam flowing from the drain is a clear sign that a valve is bad in the "closed" position and no cooling water is flowing from there.

5. Residual moisture is present in the load

It happens usually with autoclave users who pack porous items such as cloth and paper tightly together, causing them to behave like sponges and retain moisture. The simplest way to avoid this problem is to use a loading method that separates the loads, like racks or a cart and cart arrangement.

An alternative is investing in autoclaves with vacuum capabilities that dry the goods out by the end of the cycle. A sterilizer only needs to pull the vacuum in the chamber and vaporize any residual moisture.

Please contact YongFeng Medical today if you encounter any of these or other common autoclave problems. Our team of experts are knowledgeable enough to solve any problems you may be facing and bring your autoclave back to working order.


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