Machinery Protection Devices - British Automation & Robot ...

98Machinery ProtectionDevicesEN 953 (Safety of machinery. Guards. Generalrequirements for the design and construction of fixedand movable guards). This is the starting point. Thisspecification will describe such things as guardheight, mechanical requirements and fixings.EN 294 (Safety of machinery. Safety distances toprevent danger zones being reached by the upperlimbs).EN 349 (Safety of machinery. Minimum gaps to avoidcrushing of parts of the human body).EN 811 (Safety of machinery. Safety distances toprevent danger zones being reached by the lower limbs).5.0.2 Movable guards5.0.2.1 Type AWhere possible, these must remain fixed to the machine. Whenthese guards are open they must be combined with a locking deviceto prevent moving parts starting up while the danger zone is beingaccessed. A stop command must be given when the guard is open.5.0.2.2 Type BThese must be designed and incorporated into the control system sothat moving parts cannot start up while they are within the operator’sreach. The exposed person must not be able to reach moving partsonce these are in motion. These guards can only be adjusted withthe aid of a tool or key. If any of the components on the guard fail,the machine will be prevented from starting. If the machine hasalready started up, all moving parts will be stopped. The function ofthe associated locking device may be more or less sophisticated,depending on the type of hazard, frequency of opening, etc.3