The Definition of Danger Zone (Machine Guarding)

Definition of Danger Zone (Machine Guarding)

In the context of machine guarding, a danger zone is any area in or around a piece of machinery where a worker's body could come into contact with moving parts, pinch points, rotating shafts, cutting surfaces, or other hazardous mechanical actions. Danger zones exist wherever machinery has the potential to catch, crush, cut, or otherwise injure a worker who enters the space, whether the machine is running or momentarily stopped, since stored energy or unexpected startup can still pose a threat. Identifying and controlling danger zones through physical guards, safety distances, interlocks, and clear signage is a foundational element of machine safety, intended to keep body parts out of reach of hazardous motion during both normal operation and maintenance activities.

Example of Danger Zone (Machine Guarding)

A maintenance technician reaches into the danger zone of a conveyor system to clear a jam without first verifying the machine had been locked out; the conveyor unexpectedly restarts, resulting in a serious hand injury, which leads the facility to reinforce lockout/tagout training and install additional interlocked guarding around the pinch point.

Frequently Asked Questions: Danger Zone (Machine Guarding)

What types of guards are used to protect workers from machine danger zones?

Common guard types include fixed guards that permanently enclose hazardous areas, interlocked guards that stop the machine when opened, adjustable guards that accommodate different material sizes, and presence-sensing devices such as light curtains that halt operation when a worker enters the danger zone.

Why is it dangerous to enter a machine's danger zone even when the machine appears to be off?

Machinery can retain stored mechanical, hydraulic, pneumatic, or electrical energy even when powered down, and without proper lockout/tagout procedures, a machine can unexpectedly cycle, release stored energy, or restart, posing a serious risk to anyone within the danger zone.

Who is responsible for identifying danger zones on workplace equipment?

Employers are generally responsible for conducting hazard assessments to identify danger zones on all machinery, ensuring appropriate guarding is installed and maintained, and training workers to recognize and avoid unguarded or de-guarded hazardous areas.