Hollow Corrugated TubeA tubular elastic sensitive element formed by connecting foldable corrugated sheets along the folding and stretching direction. The bellows are widely used in instruments and meters, primarily serving as measuring elements for pressure gauges, converting pressure into displacement or force. The bellows have thin walls and high sensitivity, with a measurement range of tens to tens of megapascals. Its open end is fixed, while the sealed end is free, and it utilizes auxiliary helical springs or leaf springs to enhance elasticity. In operation, under the force of internal pressure, it extends along the length of the tube, causing the movable end to produce a displacement proportional to the pressure. The movable end drives a pointer, which directly indicates the magnitude of the pressure. Bellows are often combined with displacement sensors to form pressure sensors with an output of electrical quantity, and are sometimes also used as isolation elements. Due to the bellows' requirement for a larger volume change during expansion, their response speed is lower than that of Bourdon tubes. Bellows are suitable for measuring low pressure.
Bellows include metal bellows, expansion joints, corrugated heat exchanger tubes, diaphragm bellows, and metal hoses, etc. Metal bellows are primarily used for compensating pipeline thermal deformation, vibration reduction, and absorbing pipeline settlement deformation, and are widely applied in the petrochemical, instrumentation, aerospace, chemical, power, cement, metallurgy, and other industries. Plastic and other material bellows play an irreplaceable role in medium transportation, power line penetration, machine tools, household appliances, and other fields.