1. Measuring principles
Introduction 1

2. Agenda
Measurement 2.
Flow technologies 3.
Fluid properties

3. Measurements | flow
Certain quantity, which passes section of pipeline or channel in certain time
whereby quantity is generic term for mass or volume
on gases, volume is depending on pressure and temperature
volume on liquids is not depending on pressure because they are not compressible

4. Flow measurement | orientation
Purpose of measurement?
Required accuracy, reproducibility?
Pipe work lay-out (incl. flow profile, straight in-/outlet length)?
Location, surrounding environment?
Medium to be measured?
Norms, rules, regulations, legislation?
Engineering effects (process, pump capacity, personnel, etc.)?
Calibration, recalibration?
Financial consequences?
Cost of ownership?

5. Agenda 1.
Measurement
Flow technologies 3.
Fluid properties

6. Technologies | electromagnetic flowmeter
Used with electrically conductive fluids
Based on Faraday’s law
Electrode voltage directly proportional to fluid velocity

7. Technologies | OPTIFLUX

8. Technologies | coriolis mass flowmeter
Used with fluids and gases
Based on Gaspard-Gustave Coriolis
Amplitude phase shift is directly proportional with mass flow
no flow
mass flow

9. Technologies | OPTIMASS

10. Technologies | vortex flowmeter
Used with fluids and gases
Based on Theodore von Karman
Frequency of vortices is directly proportional with flow velocity

11. Technologies | OPTISWIRL

12. Technologies | ultrasonic flowmeter
Doppler
used for fluids
based on reflection of sound by entrained solids/air
frequency shift is proportional with velocity (of entrained solids/air)
Transit time
used for fluids and gases
based on ultrasonic signal travelling diagonally back and forth
time difference is proportional with velocity

13. Technologies | ultrasonic flowmeter
Inline
single beam
dual beam
triple beam
multi-beam
Clamp-on
stationary
portable

14. Technologies | OPTISONIC

15. Technologies | variable are flowmeter
Used for fluids and gases
Variable area have conical section where float is working
Three forces are acting on float: gravity force and weight from top, volumetric flow from bottom
Float is pushed up from flow and resides at point where differential pressure below upper and lower surface balances weight of float
Movement from float is transported to local display

16. Technologies | OPTIFLOAT

17. Technologies | flow switches
Flow / no flow detection
Fluid / gas detection
Examples (flow / no flow) Examples (fluid / gas)
mechanical, target or flap switch thermal level and flow switch
thermal flow switch vibration fork
variable area with contact capacitive sensor dP
electromagnetic insertion

18. Technologies | DW(M)

19. Technologies | overview

20. Agenda 1.
Measurement 2.
Flow technologies
Fluid properties

21. Flow measurement | fluid types

22. Fluid Properties Density (r) Viscosity (n or h) Reynolds Number (Re)22

23. Fluid Properties - Density
Liquids:
Density changes much less with Temperature and Pressure (effect nearly zero)
Gases:
Ideal gas law: r = p x M
Z x R x T
Where:
P=pressure [N/m2]
R=Universal gas constant [J /kmol K]
Z= compressibility factor (about 1)
r= Density [kg/m3]
T= Temperature [K] ( K = degC )
M= mole mass of fluid [kg/kmol]

24. Fluid Properties - Viscosity
Viscosity: the resistance to flow
Dynamic viscosity h [N.s/m2, Pa.s, cP]
Kinematic viscosity n [m2/s, cSt])
The relation between kinematic – and dynamic viscosity:
n = h / r

25. Fluid Properties - Viscosity
Different viscosity behaviour
Dynamic viscosity
Newtonian
t=h.dv/dy
Non-Newtonian
Time independent
Time dependent

26. Fluid Properties - Viscosity
Newtonian:
Ratio Shear stress with shear rate is constant
Viscosity changes only with respect to temperature
Examples: water, oil, gases
Shear rate, dv/dy [s-1]
Shear stress [N/m2]
Newtonian

27. Fluid Properties - Viscosity
Non-Newtonian & time independant viscosity varies with given temperature and (flow) velocity
Dilatant : e.g. starch suspension
Structurviscos : e. g. yoghurt, dressing, ketchup
Plastic : e.g. tooth paste, hand cream

28. Fluid Properties - Viscosity
Non-Newtonian & time dependant
viscosity varies with ….
Visco-elastic : e.g. polymer solutions, plastics, flour dough
Thixotropic : e.g. pseudo plastic emulsions of soaps
Rheopectic : e.g. printer ink

29. Fluid Properties - Viscosity
Shear rate, dv/dy [s-1]
Shear stress [N/m2]
Newtonian
Bingham fluid
Dilatant/ Thixotrop
Pseudo plastic

30. Fluid Properties – Effect of viscosity and flow
Shape of flow profile is affected
This may result in flow measurement errors (especially if you measure in one section
Bingham
Pseudoplastic
Newtonian
Dilatant

31. Fluid Properties - Reynolds Number
Reynolds number describes the relation between
- flow velocity (v)
- diameter (D)
- dynamic viscosity () and density (r)
Re = v x D x r 
The Reynolds number is the only parameter that describes the flow
Consequently the flow profile is described by the Reynolds number

32. Re Reynolds number T R A N S I E Re < 2300 Laminar flow profile
Turbulent flow profile T R A N S I E

33. Flow profile Reynolds Number: Turbulent flow Laminar flow
Turbulent flow - Flattened shape - Re >  4.000
Laminar flow - Parabolic shape - Re <  2.300
Transition region - in unfavourable process conditions e.g high viscosities, low flow rates < Re < Unpredictable measurement uncertainty
Reynolds Number:

34. Reynolds Number
Water
Always turbulent Re >  2.300

35. Reynolds Number
Oil
Viscosity: 50 cSt
Can have both Turbulent & Laminar flow profiles
Viscosity ↑ Re ↓
Meter size ↑ Re ↑
Flow rate ↑ Re ↑

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