flow meter presentation

1. Flow
Measurement

2. Basic Flow Measurement
Many methods of flow measurement
Bernoulli’s Equation
– A statement of energy conservation
1 2
p + ρv + ρgy = constant
2

3. Flow Pattern

4. Orifice Plate
Orifice Plate
Flow
Sharp Edge Bevel
High Pressure Low Pressure
Sensing Line Sensing Line

5. Typical Orifice Plates

6. Beveled Edge on Orifice

7. Typical Transmitter Installation

8. Flange Taps

9. Vena Contracta Taps

10. Pro’s and Con’s
High delta P High pressure loss
Lots of data Erosion
Low cost
Easy replacement

11. Venturi Tube

12. Flow Nozzle

13. Elbow Taps

14. Pitot Tube

15. Annubar

16. Annubar

17. Annubar

18. Annubar

19. Annubar

20. Output of the Transmitter ∆P

21. Square Root Extractor

22. Flow Loop with Square Root
Extractor

23. Extractor at Low Inputs

24. Cutoff Relay

25. Effect of Process Conditions
Flow measurements are inferential
– Measure a pressure drop and infer a flow
Affect by density of the fluid
– Temperature
– Pressure
– Increasing density increases the indicated
flow rate

26. Density Compensating
Flow
High Pressure
Sensing Line RTD
Low
Pressure
Sensing Line
DP Cell
Pressure
Cell
Logic
4-20 mA Output

27. Flow Measurement Errors
Erosion
Over ranging the D/P cell
Vapour formation in the throat
Clogging
Plugged or leaking impulse lines

28. For you to do
Read pp. 18-32
Answer Questions pp. 82-85, #6-14