K5 - Gas Meters/Clocking PPT/Notes Flashcards
What is a meter?
device used to measure a defined volume of fuel gases regardless of pressurized quantity.
What are the two broad categories of gas meters?
- positive displacement
- rate-of-flow
Positive displacement meters are classed as being _________
volumetric
What are the three types of positive displacement meters?
- diaphragm (or bellows)
- Rotary (Geared or Lobed impeller)
- Rotary vane
Positive displacement (volumetric) gas meters record the total quantity or volume of gas that has passed through the meter. True or False?
True
Diaphragm meters are mainly used for?
residential and small commercial
Diaphragm meters provide highly accurate readings and are mostly used for gas measurement. True or False?
True
What controls the action of a diaphragm meter?
The pressure differential between the inlet and the outlet
Rotary (Geared or Lobed impeller) are mainly used in __________ and __________ applications and operate with lower pressures and lower volumes
commercial and industrial
In a rotary (geared or lobed), two lobed or geared impellers are
synchronized to rotate within a close-fitting housing, displacing a fixed volume of gas each revolution. True or False?
True
Rotary VANE meters use vanes to form measuring compartments. One rotation is equal to __ times the compartment volume
4
Rate of flow meters are often called ___________ meters
inferential
What does inferential mean?
conclusions based on evidence
Rate or flow meters include:
- Orifice meters
* Pitot and Pitot static tubes
* Venturi tube
* Area meters
* Turbine meters
* Vortex shedding meters.
True or False?
True
orifice meters have ________ taps that measure static pressure at two points:
- upstream from orifice
- downstream where pressure is near its lowest value
pressure
dirt build up can impair the accuracy of which type of meter?
Pitot tube meter
Meter most commonly used for air or stream. Reduced taper creates a pressure drop
venturi tube meter
What meter consists of a float in a tapered vertical tube and has a pressure differential that remains constant, but area around float increases proportional to flow
Variable area flow meter
________ meter senses flow by the magnetic pick-up of each blade as it passes by.
Not very accurate at low flow rates
Turbine meters
_______ ________ meters use the natural flow of gas around a non-streamlined object. Measurement of flow detects the rate at which the vortices are shed.
Vortex shedding
Recording instruments to measure flow rate (3)
- Pressure Factor Measurement (PFM)
- Base Pressure Index (BPI)
- Base Volume Index (BVI)
BPI is a vertical ________ with consumption dial on top left
rectangle
Base volume index is a _____ with hose wrapping around
square
PFM consists of a standard gas meter with a special regulator that accurately controls gas pressure. It is normally used when gas pressures are between __ and __ psig and load under 4,000cut/ft/hour
2-5psig
- Each piece of gas equipment is designed to produce a specific amount of ____, where most is
transferred through the heat exchanger - This amount of heat is called the ______ rate or ______ input. What is exchanged is considered the output.
- heat
- firing rate or burner input
What does over-firing mean?
Sending too much gas to the appliance
Under-firing means?
sending too little gas pressure to the appliance?
How far below the rated input can you go when sending gas? %
10%
_________ is using the meter to calculate how much volume of gas is moving through the meter in a given amount of time
Clocking
Consumption dials are used by?
Gas company
Test dials are used by?
gas fitter to calculate usage
Smaller of the two test dials is often called the?
Proving dial
The gas fitter clocks how long it takes for ____ revolution of the test dial
one
The flow rate formula measures the
amount of gas that has gone through a gas meter in a given time period. True or False?
True
Why do we use time when clocking meters?
Appliances are measured in but/HOUR
Low pressure through meter _____ affect calorific value per cubic foot/meter
does not
High pressure through meter ____ affect calorific value per cubic foot/meter
DOES
Why does high pressure through a meter affect calorific value?
Gas is compressed which changes the calorific value per volume
Meter doesn’t care how dense gas is, only how much ______ passes
volume
Meter does not care about pressure because it moves a ________
volume
Gas Regulation B.C requires you to match the burner input to?
Equipment manufacturer rating plate
Low pressure is classified as ___psig or ___“w.c
1/2psig or 14”w.c
Standard cu/ft for natural gas is 1000btu per cu/ft or 10.35kw/m3. True or False?
True
Standard atmospheric pressure is?
14.7
Pressure correction factor (PCF) is required when the pressure at the meter is greater than ?
1/2psig
