Glossary · Risk assessment and risk reduction
Hazardous event
In machine safety, a hazardous event is an event that can cause harm. It can be of short duration, such as an unexpected start-up, or develop over a longer period, such as a gradual loss of guard integrity.
- Machine safety
- Risk assessment
In one sentence
A hazardous event is the moment a hazard turns into possible harm, for example an unexpected start-up while a person is inside the machine.
Example
A setter reaches into a packaging machine to clear a jam and the drive restarts because a sensor signal clears the fault; the unexpected restart is the hazardous event.
How it applies
- Risk assessment: The probability of occurrence of the hazardous event is one input to the probability of harm, together with exposure and the possibility to avoid or limit harm.
- Machine safety: Typical hazardous events are unexpected startup, component failure, ejection of parts and loss of stability. Control-system faults are a frequent cause, which is where functional safety comes in.
- Analysis methods: A hazardous event is a natural top event for a fault tree analysis, which traces the combinations of causes that can lead to it.
- Technical documentation: Describe hazardous events in scenarios the reader recognizes, for example “the machine can restart when the jam is cleared”.
Hazardous event vs. hazardous situation
A hazardous situation is the state of being exposed to a hazard. The hazardous event is what happens in that situation and can lead to harm. Without exposure, the same event causes no harm.