Dry heat


Biological indicators for dry heat sterilisation


Sterilisation with dry heat (dry sterilisation) takes place in an oven in which the air must be able to circulate. It is the direct temperature effect, i.e. the irreversible denaturation of cell components, which destroys microorganisms present.

Product description

SSI Diagnostica's biological indicators are microorganisms (spores of Bacillus subtilis, DSM 13019), prepared on a heat-stable carrier material consisting of filter paper and packed in heat-stable paper as primary packaging.

The dry heat indicators fulfil the specifications in EN ISO 11138-4, i.e. an initial microbial count of 106 CFU/unit, a D-value at 160°C of at least 2.5 minutes and a Z-value of at least 20°C.


A typical sterilisation process with dry heat takes place at a high temperature, e.g. a minimum of 160°C for two hours. Non-heat-sensitive items, e.g. glass, various examination instruments or heat-stable materials, can be sterilised using dry heat.

The biggest problem with dry heat sterilisation is reaching and maintaining the high temperature and its even distribution in the oven and materials. There is an additional disadvantage in that dry heat sterilisation is a time-consuming process. SSI Diagnostica recommends the use of biological indicators for regular routine testing and validation/revalidation of dry heat sterilisation. The aim of regular routine testing is to ensure that the temperature is maintained for a sufficiently long time in the material to be sterilised.

For non-validated equipment, SSI Diagnostica recommends routine testing every month, and for validated equipment 4 times a year.

Product range

The dry heat indicators are supplied in packs of 3 and 6 for small and large sterilisers respectively.

75619 6-unit pack without culturing, 106 CFU per unit 
75618  3-unit pack without culturing, 106 CFU per unit  



SSI Diagnostica A/S
Herredsvejen 2
3400 Hillerød

Tel.: +45 4829 9100 (switchboard)

Tel.: +45 4829 9178