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Gas A Level 2 > Block 1 - Gas Meters, Orifice Flow, Clocking Summary > Flashcards

Block 1 - Gas Meters, Orifice Flow, Clocking Summary Flashcards

1
Q

Which type of meter uses piezoelectric sensors to detect pressure oscillations caused by flow disturbances?

A

Vortex Flow Meter

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2
Q

Which type of meter uses piezoelectric sensors to detect pressure oscillations caused by flow disturbances?

A

The pressure drop is more pronounced at higher flows

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3
Q

Using the appropriate parameters from the following information, what is the calculated appliance input?

test dial = 1ft3
time measured for 6 revolutions = 84 seconds
propane gas
meter pressure 5 psig
ambient air temperature 61⁰F
single boiler operating at 68% efficiency

A

859,839.75 btu

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4
Q

In the clocking formula, when is temperature correction most significant?

A

When temperature difference (∆T) is 80℉

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5
Q

What type of meter physically measures the quantity of gas by dividing it into fixed volumes?

A

Positive Displacement Meter

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6
Q

How is the area of an orifice typically related to its geometry?

A

It is calculated from the diameter of the orifice

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7
Q

What standard pressure is used for gas measurement calculations, according to B149.1?

A

14.7 psia

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8
Q

Where are the upstream and downstream taps typically located for larger pipe with flange taps?

A

2.5 pipe diameters upstream and 8 pipe diameters downstream

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9
Q

What is the purpose of an Instrument Drive (ID) meter in gas flow measurement?

A

To allow the connection of external instrumentation for pressure and temperature corrections

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10
Q

What constant is used in the orifice flow formula to align units, viscosity, and time?

A

1658.5

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11
Q

Using the appropriate parameters from the following information, what is the calculated appliance input?

test dial = 1ft3
time measured for 3 revolutions = 78 seconds
Gas calorific value = 2,275
Manifold Pressure = 10”w.c.
meter pressure = 40 psig
local pressure = 12
gas temperature inside the building = 114⁰F
gas temperature at the meter = 61⁰F

A

1,112,147btu

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12
Q

What type of meter uses Bernoulli’s principle to calculate flow based on pressure differences?

A

Orifice or Venturi Meter

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13
Q

Which of the following meters uses sound waves to measure gas flow?

A

Ultrasonic Flow Meter

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14
Q

What is the disadvantage of using vena contracta taps in large pipe installations?

A

The need to drill through the pipe wall

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15
Q

What happens to the pressure when a flow condition is established in a system with an orifice plate installed?

A

A pressure drop occurs across the orifice

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16
Q

What is the importance of converting gas flow rate to standard conditions (SCFM)?

A

To account for variations in temperature and pressure

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17
Q

Using the appropriate parameters from the following information, what is the calculated appliance input?

test dial = 2ft3
time measured for 5 revolutions = 75 seconds
Methane gas
Manifold Pressure 3.5”w.c.
meter pressure 10 psig
local pressure 14.2{
ambient air temperature 75⁰F

A

768,049btu

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18
Q

What is the range of the K factor (coefficient of discharge) for most orifices?

A

0.6 to 0.9

19
Q

What does the term “K Factor” in an orifice flow calculation represent?

A

The coefficient of discharge

20
Q

What is a key characteristic of a rotary gas meter?

A

It is ideal for high-pressure, high-volume applications

21
Q

Which of the following is an example of a positive displacement meter?

A

Diaphragm (Bellows) Meter

22
Q

According to Boyle’s law, what happens to the energy in a gas if the gas is compressed?

A

The energy in a smaller volume is more than 1000 btu

23
Q

Pressure compensation in the clocking formula is applied when meter pressure exceeds which value?

A

½ psig

24
Q

What type of meter measures gas flow by using the velocity of the fluid?

A

Turbine Flow Meter

25
Q

What is the turndown ratio of a typical bellows gas meter?

A

100:1

26
Q

What is the primary function of a gas meter?

A

Measure the volume of fuel gases like natural gas

27
Q

Rotary meters often use two counter-rotating parts known as:

A

Lobes or impellers

28
Q

When applying both pressure and temperature correction in the clocking formula, what should be ensured about the test dial volume?

A

It should be non-compensated

29
Q

What does “ACFM” stand for in the context of gas flow meters?

A

Actual Cubic Feet per Minute

29
Q

What principle is used to calculate flow rate when using an orifice plate?

A

Bernoulli’s Principle

30
Q

What is the purpose of a Temperature Compensated (TC) meter?

A

To correct the flow rate for temperature fluctuations

31
Q

What does “Custody Transfer” refer to in gas metering?

A

The point where gas is transferred from one location to another

32
Q

Which orifice plate design is commonly used for gas pressure measurement?

A

Square-edge, concentric design

33
Q

Which type of orifice tap is commonly used for pipe sizes 2 inches (50 mm) and larger?

A

Flange taps

34
Q

What level of accuracy can be expected when using the orifice flow formula in the field with careful measurement?

A

±3%

35
Q

In a rotary meter, what determines the amount of gas that passes through the meter?

A

The rotational speed of the lobes

36
Q

What is the primary function of an orifice plate in a flow measurement system?

A

To create a pressure drop for calculating flow rate

37
Q

The calorific value of natural gas listed in the B149.1 under standard conditions is:

A

1000 btu/ft³

38
Q

The Annubar is a type of:

A

Averaging Pitot Tube

39
Q

What does the “t” represent in the clocking formula for determining burner input when clocking a gas meter?

A

Time in seconds per rotation of the test dial

40
Q

The B149.1 reference lists the standard temperature for fuel gas measurements as:

A

60℉ (15℃)

41
Q

What is the typical MAOP (Maximum Allowable Operating Pressure) range for bellows meters used in residential and light commercial applications?

A

10 to 25 psig

42
Q

What type of tap is used for smaller pipes (less than 2 inches in diameter)?

A

Corner taps

43
Q

What is the main purpose of ensuring the correct installation of an orifice plate with the label on the upstream side?

A

To ensure proper flow restriction and pressure drop

Gas A Level 2 (8 decks)

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