For every steam sterilizer used in the food and pharmaceutical manufacturing industries where temperature is a parameter of the process, temperature mapping is required by the Food and Drug Administration (FDA) and other agency directives.

Temperature mapping aims to ensure that all areas of the steam sterilizer chamber achieve the required temperature to achieve lethality. The outcome of the test is a temperature map defining the temperature of the chamber at various locations.

Temperature mapping must be run with the steam sterilizer both empty and fully loaded. The steam sterilizer must be mapped annually, with every new product configuration, and after every modification of the equipment.

PRIMUS conducts empty chamber mapping as an optional service for those end-user customers who are required to fully validate their steam sterilizers per FDA and other agency directives.

Fully loaded chamber mapping, as well as other required testing, is conducted by the end user to fully validate the steam sterilizer.


The objective of this testing is to ensure that the sterilizer is capable of attaining a temperature of 121 degrees C and the corresponding saturated steam pressure during the sterilization hold period.

A temperature spread within the range of 121 degrees C to 124 degrees C during the sterilization cycle will demonstrate the uniform heat distribution within the chamber.

Any location where the temperature indicators are not achieving minimum sterilization temperature of 121 degrees C throughout the sterilization temperature hold will be considered a “cold spot” and must be investigated and corrected.

Procedure Basics

The typical procedure for temperature mapping starts with a pre-calibration of the NIST traceable measuring equipment. Then, the measuring equipment (thermocouple probes) is set up inside the steam sterilizer. The process cycle is started while the measuring equipment logs data. A post-calibration check of the measuring equipment completes the mapping process.

To conduct temperature mapping, at least three runs are required. This includes one initial test and two replicates. If there are unacceptable variations between the three tests, a third replicate run is conducted.

During temperature mapping, PRIMUS uses 24 chamber measuring points (thermocouple probes) per run.

Acceptance Criteria

There must be uniform distribution of heat in the sterilizer chamber during the sterilization hold period and the temperature at each temperature mapping probe location must be within the range of 121 degrees C to 124 degrees C during the sterilization hold period.

Observations and Results

The observations and results are recorded and given to the end user customer. A copy is also placed in the Device History Record (DHR) maintained by PRIMUS for the respective unit.

Have a question or having difficulties? Talk to Dave Schall, our PRIMUS sterilizer expert who is here to assist you anytime at 877.679.7800 extension 1212 or email at dschall@spire-is.com.

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