Test 3

Question 1

T/F AGA 9 “Measurement of Gas by Multipath Ultrasonic Meters’” specifically refers to only multi-path ultrasonic flow meters.

Answer 1

True

Question 2

AGA 9 provides information to manufacturers and users for:

Answer 2

Performance requirements,
Meter design, Installation criteria

Question 3

T/F The two path geometries for ultrasonic meters are chordal-path and bounce-path.

Answer 3

True

Question 4

The time it takes for sound to travel from one transducer to another through the gas stream is:

Answer 4

Transit Time

Question 5

T/F Ultrasonic meters require a minimum gas density (a function of pressure) to ensure acoustic coupling of sound pulses to and from the gas.

Answer 5

True

Question 6

If the direction of an ultrasonic pulse is in the direction of flow, the pulse will experience an increase in velocity which will ______________ the transit time.

Answer 6

Decrease

Question 7

T/F Acoustic noise generated by a valve or piping configuration that is the same frequency as the ultrasonic meter’s operating frequency, may interfere with pulse detection.

Answer 7

True

Question 8

T/F Per AGA 9, flow conditioners are always needed when using ultrasonic meters for custody-transfer measurement.

Answer 8

False

Question 9

T/F The equations from AGA 7 “measurement of Natural Gas by Turbine Meter” are used to calculate gas flows for ultrasonic meters.

Answer 9

True

Question 10

What AGA Report is used to independently calculate the Speed of Sound (SOS) when checking the health of an ultrasonic meter?

Answer 10

AGA 10

Question 11

T/F Multi-path ultrasonic meters are capable of providing measurement uncertainties in the range of +/- 0.2% or better.

Answer 11

True

Question 12

Boyle’s Law states that if the temperature of a given amount of gas is held constant and the pressure increases, how is the volume of gas changed?

Answer 12

Decreases

Question 13

Charles’s Law states that if the pressure of a given amount of gas is held constant and the temperature increases, how is the volume of gas changed?

Answer 13

Increases

Question 14

Gas flow that undergoes mixing is known as ____________ flow.

Answer 14

Turbulent

Question 15

T/F The gas flow in pipelines is typically laminar.

Answer 15

False

Question 16

The rate at which an acoustic sound signal will travel from one transducer to another through the gas stream is called

Answer 16

Speed of Sound (SOS)
Velocity of Sound (VOS)

Question 17

T/F When replacing transducers, they must be replaced in pairs.

Answer 17

True

Question 18

Ultrasonic meters are typically sized and operated from __________.

Answer 18

10 fps to 70 fps

Question 19

T/F The steps listed in the AGA 9 Commissioning Checklist should be completed prior to first flow.

Answer 19

True

Question 20

T/F Maximum output frequency should always be checked during commissioning to ensure no signal degradation at higher frequencies.

Answer 20

True

Question 21

Once the Ultrasonic Meter (USM) is connected to the power source, what factor needs to be checked to make sure the meter and RTU match?

Answer 21

k

Question 22

T/F Part of the verification process involves downloading a current configuration file and comparing it to the last verification file and the baseline file collected at commissioning.

Answer 22

True

Question 23

What diagnostics are included in “basic” ultrasonic meter diagnostics?

Answer 23

Individual path velocities
Individual path speed of sound
Signal to noise ratio

Question 24

What diagnostics are included in “advanced” ultrasonic meter diagnostics?

Answer 24

Swirl angle, Turbulence, AGA 10 (SOS) versus meter SOS

Question 25

T/F The ultrasonic signal level generated by the transducers is typically the same time after time.

Answer 25

True

Question 26

Indicators that are derived only from the internal measurements of the meter are called _____________?

Answer 26

External diagnostics

Question 27

T/F Metering pressure and flow velocity do not affect signal strength.

Answer 27

False

Question 28

T/F Typically, the gain on the middle two paths in an ultrasonic meter are higher than the outer paths. This is due to increased path lengths.

Answer 28

True

Question 29

T/F Comparing the individual paths' SOS to the average SOS makes it easier to spot problems in the meter.

Answer 29

True

Question 30

T/F The profile factor is typically about 1.02 and the symmetry is typically about 1.00 for ultrasonic meters with no operating issues.

Answer 30

True

Question 31

Indicators that are derived only from the internal measurements of the meter are called _____________?

Answer 31

Internal diagnostics

Question 32

To transmit signals in an ultrasonic meter transducer, what type of current is applied to the piezoelectric element so that it vibrates mechanically?

Answer 32

Alternating current

Question 33

Programs used to perform SOS calculations need to be compliant with what AGA Report?

Answer 33

10

Question 34

To compensate for the different gas flows, the transducer signal is amplified in order for the receiving transducer to acquire a valid signal. What is this called?

Answer 34

Automatic gain control

Question 35

The gain of an ultrasonic meter can indicate interference from __________?

Answer 35

Valve noise, High gas velocity

Question 36

T/F The test frequencies of an ultrasonic meter are never changed from the original first year test schedule.

Answer 36

False

Question 37

Noise that is concentrated around a particular frequency and can be synchronous with the transmitted signal is called ____________?

Answer 37

Colored

Question 38

Noise that occurs across the frequency spectrum and is asynchronous to the transmitted signal is called_____________?

Answer 38

White Noise

Question 39

T/F A measure of signal "quality" is signal to noise ratio (SNR).

Answer 39

True

Question 40

Filtering is effective on ____________?

Answer 40

Colored Noise

Question 41

Stacking is effective on ____________?

Answer 41

White Noise

Question 42

A complete cycle of firing all enabled transducers in a single round of transducer operation is the _______________.

Answer 42

Sequence

Question 43

T/F The transducers in an ultrasonic meter are mounted on the meter body at precise locations.

Answer 43

True

Question 44

What are the number of samples that were accepted expressed as a ratio called?

Answer 44

Performance

Question 45

Normally the meter body is installed so that the electronics are mounted on the ________ of the meter.

Answer 45

Top

Question 46

T/F It is not necessary to perform a meter inspection at initial installation. The flow calibration test is sufficient.

Answer 46

False

Question 47

The bounce of the signal path _____________ the path, improving the resolution.

Answer 47

Doubles

Question 48

T/F In multi-path bounce path ultrasonic meters, one double-bounce path is operated in a clockwise direction, while the other is operated in a counter-clockwise direction.

Answer 48

True

Question 49

T/F It is not necessary for the technician to force the maximum frequency out of the Signal Processing Unit (SPU) to see that the maximum frequency is sent all the way to the RTU.

Answer 49

False

Question 50

The process of travel time measurement for all paths that is repeated a number of times per second is called _________________

Answer 50

Sample Rate

Question 51

T/F The difference between the expected (theoretical) SOS and the measured SOS can be as small as 0.25%

Answer 51

True

Question 52

Automatic Gain Control Ratio (AGC limit/AGC level) are presented in __________.

Answer 52

dB

Question 53

If the USM has a swirl path, a negative swirl angle indicates ______________ swirl.

Answer 53

Counter-clockwise