ACADs (08-006) Covered Keywords Flow rate, total flow, differential pressure, percent flow, cotameter , Bernouli . De

1. Measuring Flow ACADs (08-006) Covered Keywords Flow rate, total flow, differential pressure, percent flow, cotameter, Bernouli. Description Supporting Material

2. Measuring Flow Terminal Objective: Given the appropriate equipment and procedures the I&C Technician will calibrate and maintain flow instrumentation. Mastery will be demonstrated by successful completion of a Lab Performance Exercises and written Exam.

3. Differentiate between Flow Rate and Total Flow • Describe the relationship between differential pressure and flow • Given a percent range of DP sensed by an orifice plate, calculate the percent flow • Describe the theory of operation of a given flow measurement device • Describe the considerations for removing/restoring a rotameter from/to service

4. Flow Rate vs. Total Flow • Flow Rate is the amount of fluid, either in mass or volume that passes a point in a given time. Examples: Pounds mass per hour, gallons per minute • We measure flow rate using ultrasonics, venturi, orifice plates, etc. • Total Flow is the flow rate multiplied by an amount of time. It is the accumulated or ‘totalized flow. Result will be in either mass or volume. • Gas pumps and water meters measure total flow

5. Daniel Bernouli • Discovered the square root relationship between DP and flow • Bernoulli's Principle states that as the speed of the fluid increases the pressure in the fluid decreases • Therefore, across a restriction in flow, as the fluid velocity increases, pressure decreases • http://home.earthlink.net/~mmc1919/venturi.html

6. -or-

7. Flow Instruments

8. Example 1 • Pressure drop range: 0-100 in H2O • Flow: 0 to 100 GPM • Currently reading 25 in H2O • What is the flow?

9. Example 2 • Pressure drop range: 0-100 in H2O • Flow: 0 to 1000 GPM • Currently flow is 80 GPM • What is the differential pressure? • What devices may be used for the square root function?

12. Discovered two centuries ago by Italian scientist Giovanni Battista Venturi (1746 - 1822).

13. Venturi Tube

14. Flow Nozzle

15. Elbow Tap

16. Henri de Pitot (1695-1771)

17. Annubar

18. Rotameter When flow exists, there is a constant differential pressure across the float

19. Replacing a Rotameter • Isolate the instrument • Drain • Verify correct replacement part • Install • Verify pressure tight • Un-isolate slowly to prevent slamming the float • In service leak check

20. Flow Instruments: DP Cell

23. Ultrasonic Flow Measurement Devices Examples: Controlotron, UFM

24. Coriolis • Offer direct mass flow, volume flow, density, and temperature measurement of liquids, gases, and slurries • No moving parts • Mass flow rate causes the vibrating tubes to twist • The twist of the tubes is proportional to mass flow Watch the Coriolis Flow video-10 min Watch the Coriolis Flow video-10 min

25. Electromagnetic Flow MeasurementFaraday’s Law

28. Other methods of measuring flow • Rotary Vane Positive Displacement-turbine • Nutating Disk or piston • Hot wire method, temperature method • Pelton Wheel • Vortex shedding • Calorimetric method • Open Channels • Weirs • Target meter

29. Read OE18368 at end of ‘Flow’ section in handout. Discuss: What happened? Could it happen here? What can we do to mitigate it? Discuss control of test leads.

30. On toMeasuring Temperature