- April 19, 2009
April 19, 2009 - ‘Sensing edges’ or ‘Safety edges’ mount on the edge of large moving objects – such as doors – that provide an instantaneous warning signal to a control system when the object collides with a person or object in its path. In response to this signal, the control system can stop or reverse the motion and avoid causing damage.VITECTOR's safety edge products are based on two technologies. The first of these is based on an optical system. The edge component is typically a long rubber tube, mounted on an exposed edge of the moving object. An infrared light source is inserted at one end of this tube, with a sensor at the other end. If the tube is deformed at some point due to a collision between the moving edge and a solid object, the light path is interrupted and the optical sensor sends out a warning signal. Because there is a significant amount of internal reflection of light inside the edge tube, gradual bending of the edge (due to wind pressure on a large door, for example) won’t trigger the alarm. However, a localized deformation of the tube will interrupt the light to a more significant degree. This means that the system self-calibrates to distinguish between insignificant events and potentially dangerous collisions. The cross section of the rubber tube can be chosen to enhance the ability of the system to respond quickly to dangerous situations.The second relies on a sensitive pressure switch. For this system, the hollow rubber profile mounted on the edge of the door or other piece of equipment is sealed, with a small tube running to the pressure switch. In this case, when the tube collides with a solid object, an airwave pulse is sent to the switch, which in turn sends a warning signal to the control system driving the moving door or equipment. By adjusting the pressure switch, the required degree of sensitivity can be ‘dialled into’ the safety edge system.The optical VITECTOR system is designed as a ‘monitored’ system. That is, if there is any malfunction within the system, such as a power failure or a broken wire, a warning signal is sent to the control system. However the system is still robust against other environmental hazards such as tears in the rubber or dust and water inadvertently entering the tube. This makes the system ideal for critical safety applications. The pneumatic (pressure switch-based) system lacks this fail-safe feature, but is less expensive and suitable for non-critical installations. VITECTOR safety edges can reduce risks associated with the movement of large, heavy objects and help designers and operators meet the most demanding safety standards.