Protecting workers from lock-in risks - safe solutions for machine guarding

When doors and gates in the guard fencing around a machinery system are locked during operation, this results in a secondary risk, that is sometimes overlooked.

Somebody who is working inside the machine, for instance to resolve a fault or for maintenance, may be locked inside. That is bad enough but imagine a colleague outside would not notice him/her and restart the machine. This might result in a very dangerous situation. To allow the worker to escape from the fenced-in area as quickly as possible the door switches should be equipped with “escape release” locks.

Escape release is triggered by hitting a button or pressing down a door handle on the inside of the door. It will then open, and the machine is stopped immediately. Of course, it must not be possible to use the escape release from outside the protected area, to prevent misuse. From outside a door lock can be released by resetting the safety circuit or by means of "emergency release.”

Emergency release is achieved by using a special tool to forcibly open the guard locking switch. Of course, this will also stop the machine immediately. Emergency release is standard on most guard locking switches.

Find out more about dealing with locking-in hazards in the Axelent Safety Book.