Gas Meters/Orifice Flow/Clocking Flashcards
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 is the purpose of a temperature compensated meter (TC Meter)
To correct the flow rate for temperature fluctuations
Disadvantages of using vena contracta taps in larger pipe installations?
The need to drill through pipe wall (compromising integrity)
Pressure compensation is required/applied when meter pressure exceeds what pressure?
1/2 PSI (14 in wc)
Key characteristics of a rotary gas meter?
Ideal for high pressure, high volume characteristics
What principle is used to calculate flow rate using an orifice plate?
Bernoulli’s principle
Typical maximum allowable operating pressure range for bellows meters used in residential and light commercial applications
10-25 psig
What happens to pressure when a flow condition is established in a system with an orifice plate installed
A pressure drop occurs across the orifice
What type of meter measures gas flow by using velocity of the fluid
Turbine flow meter
What type of meter uses piezoelectric sensors to detect pressure oscillations caused by flow disturbances
Vortex flow meter
Which orifice plate design is commonly used for gas pressure measurements
Square edge concentric design
Rotary meters often use two counter rotating parts called?
Lobes or impellers
When applying pressure and temp correction factors, what should be ensured of the test dial?
That it’s non compensated
What does ACFM mean? (Gas meters)
Actual cubic feet per minute
What type of meter uses sound waves to measure gas flow?
Ultrasonic flow meter
Importance of converting gas flow rate to Standard Cubic Feet per Minute? SCFM
To account for variations in temp or pressure
Fuel gas standard temp according to b149.1?
60 F ( 15 C)
Positive displacement meters?
Diaphragm/bellows
Rotary
What’s the turndown ratio of a typical bellows gas meter
100:1
What type of meter physically measures the quantity of gas by dividing it into fixed volume
Positive displacement meter
What are the upstream and downstream taps typically located for larger pipe with flange taps?
2.5 Pipe D upstream
8 pipe D downstream
What type of tap for smaller pipes? Less than 2 inch
Corner taps
What type of taps for 2 inch and larger pipes
Flange taps
What type of meter uses Bernoulli’s principle to measure gas
Orifice or Venturi meter
