Pressure Cooker as Autoclave AGAIN

A.Ferszt a.ferszt at nospam.ic.ac.uk
Wed Jul 29 12:17:09 EST 1998

Ted Burrows wrote:
> A.Ferszt wrote on Mon, 27 Jul 1998
> > Good heavens! How do you keep the bottles from blowing up? We always
> > tighten the cap, and then back it off a little. Once the load is cool,
> > the caps are tightened before the bottles go on the shelf. The media
> > never get contaminated. Sealed plastic bottles have been known to
> > collapse as they cool.
> >
> > I suppose the 'correct type of autoclave' is one that has never been in
> > any of the university labs I've been in!
> There are various ways of controlling the cooling stage so that the
> contents of sealed bottles do not boil off, ramped cooling, air
> ballasting, water shower and the same for plastic containers.

I don't think we're talking about exactly the same thing here. To me,
sealed means *really* sealed. There is no possibility of the liquid
contents boiling off, because they can't escape unless the bottle or cap
split (which certainly happens from time to time). That's why we always
back the screwcaps off a tiny bit. The concept of an autoclave that can
sterilise truly sealed bottles of liquid (and bottles that can take it)
is new to me. It doesn't surprise me that they would be found in
manufacturing facilities. Lucky people!

> The sealing of the loose caps is common in media prep labs when quite
> often the media has to be taken out whilst still at the 80°C range.
> Sealed fluids autoclaves are more normaly found in pharmaceutical
> production suites.
> Ted Burrows.   Registered Authorised Person (Sterilizers)
> Integrated Designs
> Thermal Validation specialists

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