1. Flow Measuring Devices Dr. Alvarado

2. 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

3. Manometers The height of a liquid column or difference of height of two columns is used to measured the pressure: PROF. ALVARADO

4. 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

5. Venturi Meter Dr. Alvarado

6. 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

7. Orifice Meter Dr. Alvarado

8. 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

10. References • en.wikipedia.org/wiki/Venturi_effect • en.wikipedia.org/wiki/Orifice_plate • www.orificeplates.com • www.omega.com Dr. Alvarado