This part of ISO 10294 specifies the test requirements related to thermal release mechanisms used in fire dampers tested in accordance with ISO 10294-1. Only the thermal release mechanism is subjected to the tests described. The test methods are designed to ensure that under fire conditions the thermal release mechanism complies with the expected functions so that the damper will close completely so as to prevent the spread of fire. This part of ISO 10294 also includes a method for ensuring that the thermal release mechanism does not close the damper in non-fire conditions. The effect of corrosion on the operational reliability of the release mechanism is also evaluated. This method is only applicable to thermal release mechanisms installed within the damper or duct. It does not cover thermal release mechanisms that are located outside the ventilation duct. The test can provide information on comparative performance between one thermal release mechanism and another and thus provides for the testing of thermal release mechanisms that have not been included in the damper assembly that was tested in accordance with ISO 10294-1. The method specified in this part of ISO 10294 will determine whether the thermal activation system for the closing device of a fire damper system — is suitable for a fire damper assembly to be tested according to ISO 10294-1, — is suitable for a fire damper already qualified according to ISO 10294-1 with an alternative system of the same class (temperature-load), — is capable of maintaining its performance after the reliability tests.