Time Constant of Manometer
An apparatus to measure the time constant of a manometer and study dynamic response of pressure measurement instruments.
Overview
The Time Constant of Manometer apparatus studies the dynamic behaviour of a U-tube manometer as a second-order measurement system when subjected to a step change in pressure. The time constant and damping ratio are determined from the oscillatory or overdamped response of the manometer liquid column. Students apply the step input, record the time response, and identify natural frequency, damping ratio, and time constant by fitting the response to the standard second-order transfer function. The experiment illustrates how measurement instrument dynamics can introduce lag and oscillation into a control loop, affecting overall control performance.
Specifications
| Manometer type | U-tube, glass |
| Manometer fluid | water or mercury (as per institute policy) |
| Pressure step input | via quick-opening valve |
| Pressure range | 0 to 500 mm H2O |
| Recording | high-speed camera or pressure transducer + data logger |
| Tube diameter | variable (to study effect on time constant) |
| Damping | adjustable restriction valve |
| Power supply | 220V AC, 50 Hz (for data logger) |