autoclave times

Robert Randolph rrrandolph at juno.com
Sat Sep 5 09:15:14 EST 1998

The determination of minimal autoclave times is a function of the
radius of heat penetration and level of contamination (bio burden).
One can autoclave 380 liters of media with a bio burden of <10 cfu per
liter in a vessel with a radius of 24 inches in 90 minutes at 118C./15
psi. On the other hand, a continuous sterilizer can sterilize 380
liters of media at the delivery  rate of 4 liters per minute via a .25
inch radius ID, pressurized feed source stainless steel tubing at
147C. at 60 psi.  One should determine the f sub 0 of the item to be
sterilized....overheating media is the primary source for performance
failure of media. Now, assuming  the 5 liters of medium in question is
fairly typical with regard to bio burden and is a 6-8 liter glass or
metal container with an average radius of 6-7 inches and is preheated
to 95C; I would recommend 24 minutes autoclave time at 15psi/121C.
with an exhaust time no greater than 7 minutes. Media should be
removed from the autoclave as soon as possible...after a 5 minute
waiting period in the autoclave with the door open, to dissipate any
retained superheat.  Always shake the container gently, before moving
it from the autoclave.

On 2 Sep 1998 12:00:56 -0700, cchilcott at BIODISCOVERY.CO.NZ (Chris
Chilcott) wrote:

>Could someone please tell me how long I need to autocalve 5 litres of media
>for, or should I autocalve it in smaller volumes.
>Chris Chilcott

randolph at juno.com

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