Safety-related evaluation of thermal operating stress on safety-critical equipment using the example of composite breathing air cylinders and lithium batteries.

Status:

ongoing

Aims:

Personal protective equipment (PPE) is sometimes exposed to a very strong heat, i.e. thermal stress, during use. This can lead to an impairment of their protective effect. An additional risk to the emergency services through a thermally induced failure of the PPE must be avoided.

Research thesis: In real fire fighting operations, breathing air cylinders and lithium batteries in the protective equipment can be so highly thermally damaged that they burst or explode dangerously during use or during subsequent filling or charging, which can cause property damage or even physical damage to the emergency services. The aim is to systematically examine whether the testing and approval requirements in the most common standards take sufficiently into account the safety aspects of breathing air cylinders and lithium batteries. More recent research results already indicate safety-related gaps in these requirements.

The aim of the project is to determine real thermal operating loads, maximum temperature limits for a safe operation and its influence on aging as well as the development of suggestions for possible preventive activities.

Activities/Methods:

In the laboratory and in real exercise scenarios, the combined thermal and mechanical loads are to be determined on composite breathing air cylinders and radio devices with built-in lithium batteries in order to be able to assess critical load conditions for the remaining service life of the cylinders and the lithium batteries. This requires comprehensive temperature, pressure and gas measurements, depending on the component. After the thermal load, pressure tests are first carried out on the breathing air cylinders, based on the periodic tests and accompanied in-situ by acoustic emission testing, a non-destructive test method. Then burst tests are carried out to determine the residual strength and thus the thermal damage. On the radio devices, temperature transmission tests and critical conditions for the development of fire in the lithium batteries as well as smoke gas measurements and evaluations are carried out.

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