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Measurement > Flow > Flashcards

Flow Flashcards

1
Q

What is the principle of operation for Transit Time Ultrasonic Meter?

A

Measures time difference between sound traveling up and downstream.

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2
Q

What is the principle of operation of a Doppler shift Ultrasonic meter?

A

Shifting of frequency that results from the waves emitted by or reflected by a moving object.

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3
Q

What is the main differences between the Doppler and transit time meters?

A

Doppler: needs solid particles or gas bubbles to measure. Liquids only

Transit Time: can’t have solid particles or gas bubbles. Can be a liquid or gas.

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4
Q

Considerations to be taken with installation of clamp-on ultrasonic meters

A

Thermal expansion/contraction and pipe material. (Must be solid material, no air gaps like concrete)

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5
Q

Which medium does sound travel faster in, water or air?

A

Water

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6
Q

What kind of ultrasonic meter is needed for small pipe installs?

A

Axial.
–>—–< –
| |

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7
Q

What kind of transit time meter uses multiple probes paths?

A

Multi-tap

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8
Q

Most typical meter construction

A

Spool piece.

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9
Q

What kind of transducer has most accuracy?

A

Wetted.

Ex right in process.

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10
Q

How should an ultrasonic meter be cal’d?

A

In-line with a prover

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11
Q

What is the phase restriction on a transit time ultrasonic meter?

A

Single phase (either gas only or liquid only)

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12
Q

Which law governs a mag flow meter?

A

Faraday

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13
Q

What is the physical arrangement between the flow, magnetic field, and the electric probes?

A

Flow perpendicular to magnetic field.

Electrodes right angles to magnetic field

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14
Q

What must be the characteristics of the flow tube in a mag flow meter?

What must be the characteristics of the process fluid for a mag meter?

A

Non-conductive

Conductive

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15
Q

What is proportional to flow if the magnetic field is excited by an AC signal?

A

Flow Velocity

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16
Q

Main problem with AC excitation?

A

Noise makes a need for re-zeroing often

17
Q

Problem with the pulsed DC excitation?

A

Electrochemical polarization

18
Q

Which excitation method uses positive, off, and negative states to help with electrochemical polarization and noise cancelling?

A

Pulse DC Tri-State.

19
Q

Pros and cons of a vortex shedding meter.

A

Pros: measures liquids, gases, and steam
Output Hz is linear to flow rate

Cons: can’t be made smaller then 15mm or larger then 16”
Not Bi-directional

20
Q

Vortex flow meter limitations for min and max flow rate?

A

Min: lowest Reynolds #

Max: where cavitation occurs.

21
Q

For following substances what changes density?
Solid
Liquid
Gas

A

Solid: temp.
Liquid: temp, pressure.
Gas: temp, pressure, and compressibility.

22
Q

How many pulses do you need if collect to limit the round off to .001%?

A

10 000 pulses.

23
Q

Formula for basic meter factor?

A

MF= (proved value/meter under test)(meter)

24
Q

5 common primary differential flow elements?

A 
Venturi tube
Flow nozzle
V-cone
Pitot tube
Orifice plate
25
Q 
What are the following AGA factors are for what?
-AGA 3
-AGA 3 2000
-AGA 7
-AGA 8
AGA 9
-AGA 11
A
  • AGA 3: volumetric orifice plate
  • AGA 3 2000: mass orifice plate
  • AGA 7: turbine
  • AGA 8: compressibility
  • AGA 9: ultrasonic
  • AGA 11: mass flow
26
Q

When pipe diameter changes what happens to flow rate and velocity?

A

Flow rate stays the same.

Velocity changes.

27
Q

What changes density in
Solids
Liquids
Gases

A

Solids: Temp
Liquids: Temp and Pressure
Gases: Temp, Pressure, and Compressibility

28
Q

Basic meter factor equation?

A

Prover value/meter under test X meter

29
Q

Difference between liquid and gas turbines.

A

Gas turbines have a large diameter diffuser to direct the gas. Liquids use straightening vanes.

30
Q

Ultrasonic: principle of operations of a transit time flow meter

A

Measures time difference between sound traveling up and downstream

31
Q

What type type of ultrasonic flow meter calculates flow from the difference between Fab and Fba

What type type of ultrasonic flow meter calculates flow from the difference between Tab and Tba

A
  • Transit Frequency

- Transit Time.

32
Q

Can a Doppler ultrasonic meter be used on gas?

A

No

33
Q

What are the limitations for max and min flow rate of vortex meters

A

Min: lowers Reynolds
Max: where cavitation occurs for max

34
Q

List pros and cons of vortex shedding meter

A

Pros: measures gas and liquid streams.
Out Hz is linear to flow.

Cons: can’t be smaller then 15mm and no larger than 16”
Not bi-directional

35
Q

What’s the pattern called for moving vortices carried downstream of a stationary object called?

A

Vortex street

36
Q

Under what Reynolds # does vortex meters need K-Factor characterization?

A

8000/10 000

Measurement (6 decks)

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