EFHSS Questions and Answers - Question Q00685

What's the meaning of Fo in steam sterilization procces?

Dear Leticia

The term "Fo" is defined as the number of equivalent minutes of steam sterilization usually at temperature 121°C delivered to the load contents calculated using a z-value of 10°C.
The Fo-value equivalent is used for adjustment, control and validation of steam sterilization mainly in food industry and pharmaceutical sterilization.
In CSSD we talk in "holding times", Microbiologists talk in "value of energy " accumulated during the sterilization process and describe it as Fo. An example how they calculate it:
1 Fo is the equivalent of energy accummulated if exposed to a cycle of 1 minute at 121°C with saturated steam - so 20 minutes at 121°C are Fo 20.
Is not nescessary for CSSD Manager to know how to calculate the Fo value (CSSD sterilizer have fixed cycles) but they should know what a Fo is and how relevant it is to CSSD Sterilization.
There is an excellent article about Fo at www.fedegari.com click "Technologies" and "Fo" Technical notes.
By the way, FO with a large O is the abreviation for Formalhedyd.
I hope this is of some help.

Kind regards
Josy Holdener