Level 2 Block 1 - Gas Meters, Orifice Flow, Clocking Summary Flashcards
Which type of meter uses piezoelectric sensors to detect pressure oscillations caused by flow disturbances?
Vortex Flow Meter
What is the significance of the pressure drop in a vortex flow meter?
The pressure drop is more pronounced at higher flows
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.
859,839.75 btu
In the clocking formula, when is temperature correction most significant?
When temperature difference (∆T) is 80℉
What type of meter physically measures the quantity of gas by dividing it into fixed volumes?
Positive Displacement Meter
How is the area of an orifice typically related to its geometry?
It is calculated from the diameter of the orifice
What standard pressure is used for gas measurement calculations, according to B149.1?
14.7 psia
Where are the upstream and downstream taps typically located for larger pipe with flange taps?
2.5 pipe diameters upstream and 8 pipe diameters downstream
What is the purpose of an Instrument Drive (ID) meter in gas flow measurement?
To allow the connection of external instrumentation for pressure and temperature corrections
What constant is used in the orifice flow formula to align units, viscosity, and time?
1658.5
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.
1,112,147 btu
What type of meter uses Bernoulli’s principle to calculate flow based on pressure differences?
Orifice or Venturi Meter
Which of the following meters uses sound waves to measure gas flow?
Ultrasonic Flow Meter
What is the disadvantage of using vena contracta taps in large pipe installations?
The need to drill through the pipe wall
What happens to the pressure when a flow condition is established in a system with an orifice plate installed?
A pressure drop occurs across the orifice
What is the importance of converting gas flow rate to standard conditions (SCFM)?
To account for variations in temperature and pressure
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.
768,049 btu
What is the range of the K factor (coefficient of discharge) for most orifices?
0.6 to 0.9
What does the term “K Factor” in an orifice flow calculation represent?
The coefficient of discharge
What is a key characteristic of a rotary gas meter?
It is ideal for high-pressure, high-volume applications
Which of the following is an example of a positive displacement meter?
Diaphragm (Bellows) Meter
According to Boyle’s law, what happens to the energy in a gas if the gas is compressed?
The energy in a smaller volume is more than 1000 btu
Pressure compensation in the clocking formula is applied when meter pressure exceeds which value?
½ psig
What type of meter measures gas flow by using the velocity of the fluid?
Turbine Flow Meter
What is the turndown ratio of a typical bellows gas meter?
100:1
What is the primary function of a gas meter?
Measure the volume of fuel gases like natural gas
Rotary meters often use two counter-rotating parts known as:
Lobes or impellers
When applying both pressure and temperature correction in the clocking formula, what should be ensured about the test dial volume?
It should be non-compensated
What does “ACFM” stand for in the context of gas flow meters?
Actual Cubic Feet per Minute
What principle is used to calculate flow rate when using an orifice plate?
Bernoulli’s Principle
What is the purpose of a Temperature Compensated (TC) meter?
To correct the flow rate for temperature fluctuations
What does “Custody Transfer” refer to in gas metering?
The point where gas is transferred from one location to another
Which orifice plate design is commonly used for gas pressure measurement?
Square-edge, concentric design
Which type of orifice tap is commonly used for pipe sizes 2 inches (50 mm) and larger?
Flange taps
What level of accuracy can be expected when using the orifice flow formula in the field with careful measurement?
±3%
In a rotary meter, what determines the amount of gas that passes through the meter?
The rotational speed of the lobes
What is the primary function of an orifice plate in a flow measurement system?
To create a pressure drop for calculating flow rate
The calorific value of natural gas listed in the B149.1 under standard conditions is:
1000 btu/ft³
The Annubar is a type of:
Averaging Pitot Tube
What does the “t” represent in the clocking formula for determining burner input when clocking a gas meter?
Time in seconds per rotation of the test dial
The B149.1 reference lists the standard temperature for fuel gas measurements as:
60℉ (15℃)
What is the typical MAOP (Maximum Allowable Operating Pressure) range for bellows meters used in residential and light commercial applications?
10 to 25 psig
What type of tap is used for smaller pipes (less than 2 inches in diameter)?
Corner taps
What is the main purpose of ensuring the correct installation of an orifice plate with the label on the upstream side?
To ensure proper flow restriction and pressure drop
What are rotary lobed gas meters designed for?
They are designed to handle higher volume and pressure than diaphragm meters.
What is the pressure range for rotary lobed gas meters?
0-175 psi for medium pressure applications and 0-1,480 psi for high-pressure models.
What is the turndown ratio of rotary lobed gas meters?
They offer an excellent turndown of 50:1.
What are the capacity ranges for rotary lobed gas meters?
Capacities range from 600 CFH to 56,000 CFH.
In what applications are rotary lobed gas meters ideal?
They are ideal for large scale commercial and industrial medium pressure applications.
