People providing maintenance or repair services could: • work alone • work on machinery and equipment at height, or over machinery and equipment to connect services, such as electricity, air or water • access machinery and equipment from the rear or sides • be required to enter confined spaces of larger machinery and equipment • be trapped by the mechanism of the machinery and equipment through poor isolation of energy sources or stored energy, such as spring-loaded or counter-balance mechanisms, compressed air or fluids, or parts held in position by hydraulics or pneumatic (air) rams • move heavy parts when changing the set up of machinery and equipment, or repairing failed parts, such as electric motors or gear box assemblies • disable or remove normal safety systems to access the mechanism of machinery and equipment.
Presence sensing systems. If physical guards cannot be used, then a presence sensing system can be used as a control to reduce risk. Presence sensing systems can be used where people enter areas shared by moving production equipment. Presence sensing systems are capable of providing a high degree of flexibility with regard to access.
Where frequent cleaning is required, the guard may be constructed of mesh that prevents intrusion of body parts, but allows for hosing. Food production workplaces, that use conveyors in areas where hygiene or food safety is an integral part of the operation, use fixed mesh guarding of conveyor end rollers.
Interlock guarding occurs when the act of moving the guard (opening, sliding or removing) to allow access, stops the action of the hazardous mechanism. Interlock guarding works by: • disconnecting the drive mechanism mechanically (e.g. applying a brake or disengaging a clutch or geared mechanism) • isolating the power source of the drive mechanism (e.g. stopping the motor) • a combination of mechanical and power disconnection.