ADIGITAL MICROMANOMETER FOR VERY LOW PRESSURE MEASUREMENT

摘要

A highly sensitive micromanometer to measure low differential pressure heads is developed. It works on capacitance principle by which it measures the air gap, up to 2mm with an accuracy of 0.001 mm, between either a mercury meniscus or a metallic float and a sensing element with an accuracy of 0.001 mm. The movement of mercury meniscus or a metallic float is due to the applied differential pressure in the manometer circuit. It has a digital display and can be connected to a computer through a data acquisition system for continuous recording of data. It can be used either for water or air as experimental fluids. Also, it is easy to operate and maintain as well as reasonably very economical too; and ideally suited for Indian conditions. It has applications in hydraulic and aerodynamic laboratories, especially useful in the measurement of water surface elevations in open-channels and velocity profiles in boundary layers. Four models with different measurement accuracies of pressure head are presented which show that the measurement accuracy of the pressure head can be achieved from 0.0011mm to 0.0175mm and cover the ranges up to 2.2mm to 35 mm of water head.