The Unique Problems of Welding Sensor Devices

Sensors are devices that monitor changes or variations in an object or process relative to a reference standard. Depending on their intended function, they can recognize changes in weight, vibration, motion, pressure, color, heat, light, magnetism or chemistry. They may be part of a system controlling a manufacturing process, activating a warning system, controlling vehicle motion or monitoring patient vital signs, to name just a few. Sensor devices come in various forms and utilize different laws of physics. Fluctuations in sensible heat expand or contract a liquid column and form a thermometer when viewed against a calibrated reference scale. Differential thermal expansion of a bi-metallic strip provides mechanical motion to operate a switch or move a needle on a calibrated gauge. Volume or pressure changes resulting from thermal expansion (or contraction) of liquid in a sensing well create bellows or diaphragm movement useful for operating a switch or providing control of process gradients.