The new revision of Annex 1 now specifies the test criteria that shall be used for Thermal Validation of sterilisation by heat cycles.
In this article we look at the criteria referred to as F0 and Fh
They are calculated approximations for the equivalent time spent at the target sterilisation temperature and they consider the lethality that is accrued not just throughout the exposure period but also during heating and cooling of the load. They can be used when the load items are slow to heat and cool for example large fluid loads. The algorithm used for the calculation considers how the kill rate increases with temperature and is dependent also on the species of microorganism.
F0 is the term used for moist heat sterilisation cycles and Fh is for dry heat. Dry heat is far less effective at transferring heat energy into a load than saturated steam and so Fh is specified in Annex 1 for use in depyrogenation cycles.
As mentioned, it is useful when the load is slow to heat and cool because there could be significant accrued lethality as the temperature rises towards exposure and after the cycle ends the heat may be slow to dissipate and hence lethality continues to be delivered albeit at a reduced rate.
XpertLog software can perform the calculation which requires to be configured to suit the load and microbial species present (Z and D values). Once configured the value is calculated and if using real-time loggers or thermocouples these values can be displayed also in real-time so you can see the lethality as it accrues.
To learn more about how XpertLog software ensures your compliance by integrating all necessary acceptance criteria stipulated by the new Annex 1, simply click the link below.
https://lp.constantcontactpages.com/sl/q7Dp4vp/annex1series
