There are numerous alternatives to the movable guard with interlocking.
The following monitoring systems in the following sections:
- Light barriers, light curtains, range scanners
These monitoring systems serve two purposes:
- To monitor access of people and objects into the hazard zone.
- To replace physical guards to allow for easier access, save space or reduce operating time.
However, to achieve the second purpose, these systems come with a significant limitation.
They are not suitable for protection from additional hazards, such as:
- Ejection of parts
- Spraying of hazardous and/or pressurised liquids
- Hot or very cold parts close by
- Hazardous dust, fog or fumes generated
If your application involves any of these hazards, do not rely solely on monitoring devices as your safety measure
Sensitive protective devices tend to blur the boundary between the safe area and the hazard zone. People may be unaware of the risk involved or may get used to entering a hazard zone without giving much thought to it.
Often it is not clear to operators when and how the safety device is to respond and what the safety function involves. This may lead to hazardous behavior.
With a fence and guard-locked door on the other hand, entering a hazard zone always is a conscious, willful action.