Chapter E Flashcards
What two types of gas meters are the most common in residential and commercial markets?
The diaphragm (or bellows) meter and the rotary (geared or lobed impeller) meter.
Which meter is most commonly used, the diaphragm meter or the rotary meter?
The diaphragm meter.
Which gas meter is used for industrial use?
The rotary meter.
How does a gas fitter calculate actual burner input to a gas appliance?
By clocking the gas meter, and by measuring manifold pressure and orifice size.
Is overfiring allowed?
Overfiring is not acceptable.
The test dial on a meter serves two purposes to the gas fitter. What are they?
1) To determine actual flow rate to an appliance after installation. and 2) To check for leaks in a piping system.
What is flow rate?
The actual volume of gas burned.
What two formulas are used in general clocking procedure?
The clocking formula, establishing flow rate per hour, and the burner input formula, clocking formula x calorific value.
What is the clocking formula?
3600 x Test Dial x Pressure Correction Factor (If 0.5 psig or higher on the meter) / Secs per Revolution of test dial. = Cubic feet of gas burned per hour.
What is the burner input formula?
Clocking formula x calorific value. Take the resultant cubic feet per hour from the clocking formula and multiply by calorific value of the gas.
What is the pressure correction factor formula?
(Local atmospheric pressure + working pressure) / Standard atmospheric pressure.
What is standard atmospheric pressure?
14.73 psi or 101.325 kPa.
If a heating system is converted from natural gas to LP-gas, will the new orifice need to be smaller or larger?
The orifice will be smaller because LP-gases have a higher heat density.
What 4 factors influence flow of gas through an orifice?
The K factor, pressure drop, specific gravity, and the area.
What are three types of main burner orifices?
Fixed, adjustable, and cap (or universal.)
