A sterilisation tunnel provides dry heat sterilization or depyrogenenation of containers, vials, bottles, ampoules etc. The items to be sterilised are placed on a conveyor belt that moves them through the tunnel at a pre-determined rate. Typically, heat exposure of 350 C for 15-20 minutes is required.

This application is very challenging if you are trying to use a thermocouple based system.  Thermocouples must be the Kapton coated type and sufficiently long enough to pass through the entire length of the tunnel.  Each thermocouple must be secured into position and carefully bundled so they can feed into the tunnel without getting damaged or entangled in the moving belt assembly.  During the mapping process, thermocouples often get dislodged and several attempts may be needed to get good test results.

The XpertLog wireless dataloggers can make this difficult application a simple one. However, the dataloggers cannot be exposed to high temperature without being damaged. Therefore, for this application, the datalogger requires a Kapton coated extended probe. The datalogger is placed inside an insulated canister which acts as a thermal shield. The extended probe feeds out of the canister and can be positioned on the belt or inside an item to be sterilised (see picture below).

Multiple datalogger canisters can be easily placed on the moving belt to accurately temperature map the tunnel operating conditions. The dataloggers will not be damaged if heat exposure is limited to 15 to 20 minutes @ 350 C or less.

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