DESCRIBE the theory of operation of the following flow detection device
Ultrasonic Flow Sensors
Rotameter Consists of a metal float and a conical glass tube. Tube diameter increases with height. High density float will remain on the bottom of tube with no flow. Space between the float and the tube allows for flow past the float. As flow increases, the pressure drop increases, when the pressure drop is sufficient, the float rises to indicate the amount of flow
Ultrasonic flow measuring equipment uses the principle of Doppler frequency shift of ultrasonic signals
Thermal Flowmeters (often called hot-wire anemometer) are principally used in gas flow measurement. The meter consists of a fine platinum wire that is placed into the flow
The electromagnetic flowmeter is similar in principle to an electric generator. The rotor of the generator is replaced by a pipe placed between the poles of a magnet so that the flow of the fluid in the pipe is perpendicular to the magnetic field.