Exam Question

### Working Principle of a Differential Pressure (DP) Transmitter
A Differential Pressure (DP) Transmitter is a robust instrument used to measure the difference in pressure between two points and convert this measurement into a standardized output signal, typically pneumatic (3-15 psi) or electrical (4-20 mA). The principle is based on the **Force-Balance Mechanism**.
1. **Sensing Element**: The core of the transmitter consists of two pressure chambers, designated High Pressure (HP) and Low Pressure (LP), separated by a flexible sensing diaphragm or bellows. Process pressures from two separate points are piped to these chambers.
2. **Force Generation**: The difference in pressure, $$ \Delta P = P_{HP} - P_{LP} $$, exerts a net force on the sensing diaphragm, causing it to deflect. This force is transmitted mechanically via a force bar or a similar lever system.