Sterilization Temperature 121 DegC

The temperature has to do with the conversion.

As a rule one take 250 degrees Fahrenheit which is XXX.x degrees Celsius. I hope this answer is good for you?

Also the time the goods have to be in the autoclave, depends on the mass and nature of the product (and the autoclave too) to sterilize and how "deep" it has to go.

It is a good practice to boil (100 degrees Celsius) "unknown" water and the higher temperature makes the process more safe.

My guess is that at this temperature and pressure combination water must be a vapor. I presume that all known bacteria walls will be ruptured from the internal water pressure. This is why 90°C is too cold. 150°C will certainly sterilize but will be a waste of added energy for no return.

I would say that sterilization is based on the same criteria as pasteurization........ High the temperature, shorter the time, (such as HTST = High Temperature, Short Time)

As far as the temperature and the time, I believe this is a Temperature/Time Relationship for sterilization.

Higher the temperature, shorter time requirements.......

But, the higher temperature has detrimental effect on the equipment it's sterilizing, so that may be a limiting factor, as well as lower temperature and that it has to be high enough to kill the pathogens.

And the actually Time/Temperature relationship more than likely was derived from a government standards agency. Which I'm sure is labeled on the sterilization unit.

Here, you can search for this information on TechStreet. I bought my USDA 3A info here.

And to be more precise, this and this is probably what you are looking for.

The sterilization process depends on the target....what bugs are you wanting to render inactive....different bacteria live in certain temperature ranges....water sterilization targets bugs that cause stomach problems and diarrhea....@161ºF these bugs die....but thermophilic bacteria(heat loving), can survive to 252ºF....but there are other microbes that are dangerous as well....Now it's true that most bacteria are not harmful and indeed a lot are beneficial to humans, if fact we would not survive without them....but the sterilization process is a clean sweep approach...

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC271717/

http://www.nps.gov/yell/planyourvisit/upload/RI_2013_thermophiles.pdf

Yes, some thermophiles can thrive at 252°F [122.2°C]. So the OP's temperature and pressure will be insufficient for interplanetary sterilization of a deep space probe. Any thermophile that thrives at 120°C will likely become dormant or prone to attack by an immune system at 37°C.

Think "pressure cooker".

The use of the steam autoclave (heat sterilizer) vs. a Ethylene Oxide, Dry Heat or chemical sterilizer is dependent upon several factors: configuration of items being sterilized (open or closed, cotton plugs or open, etc); the material to be sterilized (water, st stl, pumps, rubber hoses, etc); the time to bring it up to temp and pressure; the time at temp and pressure; the cooling time; is vacuum used to expedite the removal of water from the items and inner surfaces?; cooling water placed in the jacket, etc. The optimum temp is 121.1 deg C because it is also 250 deg F. I'm not a micro bug guy so I don't know why that was selected other than almost all germs, etc. are destroyed at that temp. Less than that and some bugs will continue to grow. Higher and you waste money plus some items will be destroyed by the excessive heat and /or pressure.

It is always the best procedures to have: a minimum time; minimum steam pressure; steam from a clean secondary re-boiler (not the plant boiler house); clean filtered water for generating steam; and similar precautions. Also the items being sterilized must be packed in such a way that steam can get to and inside them. The less dense the stacking of them the better the sterilization. If you are steam sterilizing water, such as for injection, make sure there are cloth plugs in the top of the containers, so a pressure differential is not generated and no contamination of the sterilized material occurs after sterilization.

Not only does it take a temp of 121 deg C but also full access for the steam to reach all surfaces to be sterilized.

Good Luck, Old Salt

That's what kills everything.

the boiling point of water is 100C at 1 barg. you need to read the table that you cited.

Are you sure?

The boiling point of water is 100C at zero barg

Bar(g) is a unit of gauge pressure, i.e., pressure in bars above ambient or atmospheric pressure

You are wrong, again.

The boiling point of water is 100°C at 1 bar. Doesn't matter if the pressure is read with a gauge, or not.

If you try to pull water down to 0 barg, it will all boil away.

Sorry Lyn, but you missed the precise point that Wal succinctly made. One barg of pressure is one nominal atmosphere of pressure plus ambient [one atmosphere] pressure. This ambiguity of pressure values is one of the things that has regularly bothered me. I realize this ambiguity will probably never be fully settled until space travel or deep sea travel become normal.

Getting back to the question, it might be this ambiguity of pressure and temperature guarantees that a temperature of 121°C is above the boiling point of water regardless of the pressure metric.

Semantics? No, you, and he, are right.

OK, I'm just looking for an excuse to bust Wal's chops anyway.

Sorry Wal.

Please refer to the document "National Standards and Recommended Practices for Sterilization" pubished by the Association for the Advancement of Medical Instrumentation (USA), which covers all aspects relevant to this.

There are two crucial issues:

1. Temperature: between 121 and 124 deg Celcius.

2. Pressure: within +/- 1 PSI of the theoretical pressure for the above temperatures. This limits the amount of non condensible gases that can be present in the chamber (air/Nitrogen)

Greetings,

We have several autoclaves on site here at our plant. Steris, Betastar, Consolidated and Getinge. So I am very familiar with this topic. I would be happy to bore you with details but actually a good search of the web should be able to answer any and all questions about this topic in detail.

In General,

As is noted above, different organisms and materials take different handling. Time temperature and pressure all figure into this equation AKA the FO value.

So although the GENERAL standard is 15 to 20 minutes @121.1C/1 bar, this can be different given situation and desired results.

A thorough understanding of your material being sterilized and the intended results are needed to make any kind of educated determination as to what temperature. Pressure and time is necessary.

Sorry, no easy answers, and to be effective, a thorough validation of the process needs to be accomplished before using anything treated in this way.