VII.5.2.2 Bellows Resistance Transducer

Bellows Resistance Transducer is resistance type transducers which has moving contacts (slide wire variable resistors). The pressure change causes a resistance change due to the distortion of the wire. The value of the pressure can be found by measuring the change in resistance of the wire grid. Eq.(VII.10) shows the resistance relationship.

(VII.10)

Where R is resistance of the wire grid (in ohms) K is resistivity constant for the particular type of wire grid, L is the length of wire grid and A is the cross sectional area of wire grid.

Fig. VII.18: Schematic of a Bellows Resistance Transducer

Fig. VII.18 shows the schematic of a Bellows Resistance Transducer. As pressure changes, the bellows will either expand or contract. This expansion and contraction causes the attached slider to move along the slide wire, increasing or decreasing the resistance, and thereby indicating an increase or decrease in pressure.