Metal finishing Q&As since 1989

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Cleaning stainless steam sterilizers

I am working at a hospital and have been asked to clean the inside of a steam sterilizer (stainless steel) and have tried some acids, soaps and bleach, etc. Nothing seems to clean it. There is a green residue and also a black powdery residue. The sterilizer is 3'x3'x4'. Fairly large so it is discouraging to spend hours cleaning it only to have it remain dirty. Is there something that really cleans this? What are the green and black residues?

Luther Burnham
medical equipment tech - New Braunfels, Texas
2004

I have some experience cleaning steam sterilizers, although not ones stained as badly as you describe. There are some acid materials that would probably clean the sterilizer, but these are dangerous to use, requiring personal protective equipment, ventilation, waste disposal, etc. This is probably not practical for a hospital environment. You may be able to grit blast the sterilizer interior, but you will need to shield areas you do not want blasted. Also you need to prevent the blast media from getting inside the sterilizer plumbing. There are some commercial stainless steel cleaners that are much less hazardous than acid, but may require use of large amounts of elbow grease.

If you do mechanically clean the sterilizer, you may have to re-passivate the surface after cleaning. There are some newer commercial products for this purpose which are much safer than the acid-based methods previously used.

Perhaps the company you bought the sterilizer from has a service dept. if so, they may be able to advise you. I hope this helps.

Thomas Kemp
Sterilizers for the medical industry. - Erie, Pa. USA
2004

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2004

There are a number of safe products that you can use effectively to clean this kind of equipment, but you will have to do some testing to determine the effectiveness. The black is probably carbon coming out of the stainless steel, but I am not sure what the green is. It could be something from the parts that you are putting in the sterilizer.

We have citric acid based products that could do the job for you, but we need more details.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois