BellowsA 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. One end is fixed and sealed, while the other end is free, and auxiliary helical springs or leaf springs are used to enhance elasticity. During operation, under the influence of internal pressure, it extends along the length of the tube, causing the movable end to produce displacement proportional to the pressure. The movement of the movable end drives a pointer to directly indicate the pressure magnitude. Bellows are often combined with displacement sensors to form electrical output pressure sensors, and sometimes they are 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 thermal deformation of pipelines, vibration reduction, and absorbing settlement deformation of pipelines, and are widely applied in industries such as petrochemicals, instrumentation, aerospace, chemicals, electricity, cement, and metallurgy. Plastic and other material bellows play an indispensable role in medium transportation, power wiring, machine tools, household appliances, and other fields.