Glossary · Guards and machine motion
Barrier guard
In machine safety, a barrier guard is a physical barrier that prevents access to a hazard. It works by separating the person from the hazard zone rather than by detecting the person.
- Machine safety
- USA
In one sentence
A barrier guard physically separates people from a hazard; its effect depends on height, openings, distance and robust fixing, not on detection.
Example
A welded mesh panel mounted around the chain drive of a conveyor prevents the operator's hands from reaching the sprockets while leaving the drive visible for inspection.
How it applies
- Machine safety: “Barrier guard” is common usage, especially in US practice, rather than a defined type in ISO 12100. In ISO terms, a barrier guard is usually a fixed or movable guard; classify it that way in design documents.
- Design: A barrier only prevents access if its height, its openings and its distance from the hazard are chosen together. Check them against the reach distance tables of ISO 13857.
- Technical documentation: Describe the barrier in the technical file with its type, material, fixing and the hazards it covers. In the instructions, state that it must be in place during operation.
- Evidence: Include barrier guards in inspection checklists: damaged mesh, missing fasteners or gaps at the floor are typical findings.
Barrier guard vs. protective device
A barrier guard blocks access physically. A protective device, such as a light curtain, lets the person approach and stops the hazard when it detects them.