Equilibration time - reaching "sterilization temperature" - 121.1 C or set point?

Hi all,

I have been struggling with acceptance criterion to interpret for autoclave qualification, namely equilibration time. I was hoping you could give me some input or an example of this criterion.

I have read numerous articles on this topic but cannot find a concrete example with actual values. Looking at some common definitions, I found the following:

Equilibration time: The period which elapses between the attainment of the sterilization temperature at the reference measuring point (usually chamber drain) and the attainment of the sterilization temperature within the porous load.

The question I have each time is, what is considered as the sterilization temperature? Would this be the set point of the hold time (e.g. 123.0 C) or the commonly accepted 121.1 C (even when the set point is higher, e.g. 123.0 C).

So by means of an example, if the hold time temperature set point is 123.0 C, does the equilibration time start when the reference measuring point reaches 123.0 C (and stops when all probes in the load reach 123.0 C) or when the reference measuring point passes 121.1 C (and stops when all probes in the load have also passed 121.1 C)?

Thanks a lot in advance for any input…

Hi Monepok,
Equilibration time means, the time gap between the first probe and the last probes reaches to set point. Generally, this should not be more than 60 sec. Its proves the vacuum efficiency of your autoclave.

Sterilization set point would be genwrally 121.1 for 15 min. But it varies with type of load. If you have proved in your validation that you can achieve sterility (6 log reduction), you can use the same value as your sterilization set temp. 123 could be your cut off (overshoot) if your loads are heat sensitive.

The general standard is 121.1 Deg C/1 bar for at least 15 mins, but this can be different given situation and desired results.

Dear Monepok, now we will solve your mistery. For more info please see standard EN 285 or ISO 17665.

Yes, equilibration time is time gap between the first probe and the last probes reaches to set point but first probe in the drain and last probe in the load. And not set point at which autoclave is set than sterilization temperature of 121oC.

Thats equilibration time and must be less than 15/30 seconds depends of chamber size (800liters).If you set 123oC it is only to be safe if temperature fall below or to short sterilization (holding ) time.

Holding time starts when last penetration TC reach 121oC and should be longer than 15 minutes. Holding time can be shorter if temperature is higher and then we can use Fo values to compare times/temperatures…if we make the case simpler, after equilibration time you can have Fo greater than 15minutes no matter which temperature is set…