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Flow Measuring Devices. Flowmeters. Devices used to measure flow rate: Venturi (based on pressure difference) Orifice Plate (based on pressure difference) Rotameter (based on drag forces) Coriolis (measure mass flow rate) Magnetic (magnetic field is used to measure flow rate)
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Flow Measuring Devices Dr. Alvarado
Flowmeters • Devices used to measure flow rate: • Venturi (based on pressure difference) • Orifice Plate (based on pressure difference) • Rotameter (based on drag forces) • Coriolis (measure mass flow rate) • Magnetic (magnetic field is used to measure flow rate) • Ultrasonic (ultrasonic waves are used to measure flow rate) Dr. Alvarado
Manometers The height of a liquid column or difference of height of two columns is used to measured the pressure: PROF. ALVARADO
Venturi Effect • The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of pipe. - The Venturi effect is a jet effect; as with an (air) funnel, or a thumb on a garden hose, the velocity of the fluid increases as the cross sectional area decreases, with the static pressure correspondingly decreasing. Dr. Alvarado
Venturi Meter Dr. Alvarado
Orifice Plate • An orifice plate is a device used for measuring the volumetric flow rate. It uses the same principle as a Venturi nozzle, namely Bernoulli’s principle which states that there is a relationship between the pressure of the fluid and the velocity of the fluid. When the velocity increases, the pressure decreases and vice versa. Dr. Alvarado
Orifice Meter Dr. Alvarado
Rotameter • Pressure difference is constant in the rotameter • Peripheral velocity is constant • To maintain a constant velocity, the cross sectional area must vary • This variation of cross sectional area occurs as the float moves up and down the rotameter. Dr. Alvarado
References • en.wikipedia.org/wiki/Venturi_effect • en.wikipedia.org/wiki/Orifice_plate • www.orificeplates.com • www.omega.com Dr. Alvarado