Questions & Answers

Do autoclaves require filters, and if so, can the filters be cleaned ultrasonically? (Michael, USA)

Autoclaves do require air filters, but they cannot be cleaned ultrasonically.  Dirty filters must be replaced. Please consult your owner’s manual for specific instructions.

Dear colleagues, while it is generally known that air in steam will reduce the sterilization efficiency in autoclaves, I could not find any quantitative data. Do you have any data to show how efficiency drops when air constitutes 1,5,10 & 20% of the steam? (Peter, Switzerland)

In general, where there is air, steam will not penetrate. Where the steam doesn’t penetrate, sterilization cannot occur. This means we need to remove the air in order for the steam to penetrate to the deepest points of the load. For that we provide prevacuum pulses, which remove the air. By European regulation more than 99% of the air must be removed. 

In case you are asking about non-condensable gases, which are present in steam, then there are special tools for testing the quality of the steam.
 

What are the safety guidelines about being in the presence of an autoclave while it is in operation? (K G KAPOOR, India)

There are two points to consider.  First and foremost, it depends on the biosafety level of the load. What exactly are you sterilizing? If you are sterilizing instruments for medical use, then I see no biological danger by being in the same room.  To inquire about the biosafety level (BSL) of your load and associated precautions, please see our blog post BSL Autoclaves for Biosafety Sterilization.  Secondly, we are dealing with a pressure vessel, regardless of the load type, and one should not stand in front of the autoclave door while the cycle is running.

I use an autoclave to sterilize empty glass bottles in various sizes, from 50ml right up to 10L. I sterilize the bottles with their lids on (not too tight), which seems to work well, except in the case of the 1L size bottles. At the end of the autoclave cycle these bottles appear to be thoroughly dry, but after 10 mins of cooling they almost all have condensation on the inside. I find this strange considering that I sterilize different size bottles in the same load without incident. Any suggestions to avoid this situation? (Erik, Netherlands)

Condensation occurs because of the difference in temperature inside and outside of the chamber. Try leaving the bottles for a few extra minutes after opening the door.