Bellows

Measuring pressure with bellows device

The bellows is a device which operates on a very similar principle to the diaphragm. The sensitivity of a bellows is greater than for a diaphragm, which is its principal attribute. Pressure changes within the bellows produce translational motion of the end of the bellows which can be measured by capacitive, inductive (LVDT) or potentiometric transducers according to the range of movement produced.

A typical measuring range for a bellows-type instrument is 0-1 bar (gauge pressure). The bellows is now rarely used because of its high manufacturing cost and proneness to failure. Its traditional advantage of being able to measure low pressures with a high sensitivity can now be satisfied more cheaply by diaphragm-type devices, using recent developments in electronics.

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