The number one reason your Tuttnauer autoclave tests positive for biological indicators

The CDC recommends that you test your autoclave for biological indicators at least once a week and this is one of those times when you want a negative result. A positive result means live spores were found in your test sample and that means there is a problem with your autoclave. Fortunately, aside from human error, there is one main reason your Tuttnauer autoclave fails the spore test: a faulty or clogged air blast valve.

An early indicator that you might be having problems with your autoclave is if the indicator strip on your sterilization bag does not change color. Remember, first, if the strip changes color, that only means that your autoclave was reaching the proper temperature, not that your instruments were being sterilized correctly. However, if the strip does not change color during the cycle, you definitely have a problem with your autoclave.

When you get a negative test result, the first thing you need to do is make sure your staff has done everything they were supposed to do. Did they set the time right? Did you make sure the water tank was full? Did they let it run through the full cycle before opening the door? And were all your instruments packed and loaded correctly?

If you can rule out operator error, your next stop should be the air blast valve and it is located inside the reservoir. The air blast valve allows cold air inside the chamber to escape while the chamber heats up. Hot steam pushes cold air out through this valve, and if that cold air can’t escape, there will be pockets of air inside the chamber. These pockets of cold air prevent the pressurized steam from completely sterilizing your instruments, which is why it failed the spore test.

This valve is also open throughout the cycle to allow small amounts of steam to escape, which is why a slight hissing noise is sometimes heard during operation. This purge keeps the steam moving and helps maintain a constant temperature inside the chamber. Without this constant movement, cooler vapor pockets would develop and, again, there is another reason why the spore test might fail.

These cooler air pockets can have several different effects. You may think there is a problem with the heating element or a problem with the temperature sensor or even a problem with the pressure gauge. But if you check the air blast valve first, you’ll probably be able to solve your problem right there.

How difficult is it to clean the air blast valve? Well, do you have a minute? Because that’s all it’s going to take!

First, remove the cap from the water reservoir and locate the valve. Using a pencil, screwdriver, or something similar, put it through the loop at the end of the valve. This loop is actually at the end of the cleaning cable. Now all you have to do is pull the cable in and out ten times to clean the valve. This works best if you do it while your Tuttnauer autoclave is running so the pressure can remove any debris that is clogging the valve.

Put the cap back on the reservoir and your problem is solved. Just be sure to clean that valve every week, or more often if needed and you shouldn’t have any more problems.