How pressure is measured using LVDT?

There are various methods used for pressure measurement in a process plant are,

• Resistive transducer.
• Capacitive transducer.
• Bellows.
• Diaphragm.
• Inductive transducer.
• Photo electric transducer.
• Piezoelectric transducer.
• Capsules.
• Bourdon tube.

The pressure measurement using bourdon tube and LVDT is shown in above figure. In this the, the bourdon tube act as primary transducer and LVDT which follows the output of bourdon tube act as a secondary transducer. The bourdon tube senses the pressure and converts it into a displacement. The free end of bourdon tube shows this displacement. A cord is used to connect the free end of bourdon tube to the core of LVDT as shown in figure. When the free end shows the displacement, the core of LVDT also moves. This movement of core is proportional to the displacement of free end, which is proportional to the applied pressure. The LVDT gives analogues output which is a conversion of displacement into respective emf. This set up is used for measurement of pressure which is converted into electrical signal by LVDT.