Gas Fundamentals Flashcards
At what point is primary air supplied to the combustion zone?
Upstream from point of combustion
What does theoretical air consist of?
Primary and secondary air
Excess air + theoretical air =
Total combustion air
What is another name for calorific value?
Heating value
Propane in a tank will build from liquid to vapour and expands _________ times its original volume?
270
Standard temperature and pressure?
60 degrees F and 14.7 psia
Three constituents of fire?
Heat, fuel and oxygen
Incomplete combustion can produce harmful products, name 2?
Aldehydes and carbon monoxide
Water vapour, carbon dioxide and nitrogen are produced when all fuel gas is burned and what takes place?
Complete combustion
Appliance output divided by appliance input gives you?
Appliance efficiency
When sizing combustion air and the input falls between 2 figures, what should you do on the chart?
Round up
What is the difference between tight and loose construction?
Tight has vapour barrier, loose does not
Where are combustion air terminals fastened?
To the appliance having the largest BTU input
If height for grade cannot be adhered to, what can be installed?
A gooseneck
Automatic dampers can be installed on combustion air, where will they be wired?
Interlocked to the main burner. In case of fail, the damper will be in the open position.
What is added to gas from the transmission company to ensure safe handling? And at what rate is it added?
Mercaptan
1 lb/1,000,000 cubic feet
Ambient air admitted to a venting system at a draft control device is known as what type of air?
Dilution air
What temperature is water most dense?
4 degrees C or 39 degrees F
Density x Volume =
Mass
When water changes to steam, its volume increases approximately ________ times?
1700
Fusion is the transformation from solid to ____________?
Liquid
Condensation is the transformation from ___________ to liquid?
Gas
In heat transfer, what type is through direct contact?
Conduction
What type of heat transfer takes place because of differences in density?
Convection
Transmission of heat energy by means of electromagnetic infrared rays is what type of heat transfer?
Radiation
Substances expand and contract at different rate, what is this known as?
The coefficient of linear expansion
According to the principles of hydrostatics, what will happen to the pressure on a horizontal pipe if the length of the pipe is increased?
Horizontal runs do not increase pressure so it will stay the same
What is the heating value of Propane?
2500
Propane cylinder may be filled to?
80% of the volume or 42% of the water capacity
What is the minimum pressure rating for a propane cylinder?
240 psig
Name 3 types of draft when referring to venting appliances
Forced, natural and induced
How high must vents extend above a roof that is flat?
Minimum 2’ and 2’ higher than any portion of a building within 10’
Type B vent clearance to combustibles?
1”
Type BW vent clearance to combustibles?
1/2”
For each additional 90 degree change of direction over 2, how must the table be derated for draft hood appliances?
10% or derate by multiplying by .90
What is a concern for venting a single mid efficient into a masonry chimney?
Condensation
Where must a vent terminal be located in regards to a mechanical air supply?
Not within 6’
What is ROT and what does it mean with respect to sizing vents?
Rule of Thumb sizing and it means to simply size the vent connector and common vent the same size as the draft hood or flue collar outlet
All piping and equipment before and including the meter is the ownership of?
The utility company
How many inches of water column is a low pressure natural gas line system?
7” to 14” WC
Low pressure propane gas line system?
11” WC
What is the smallest diameter of threaded pipe that can be used for natural gas unless it is schedule 80?
1/2”
What type of gas line fitting cannot be nested?
Bushings
When pipe protrudes through a ceiling or wall, how much pipe must be exposed? Through a floor?
Ceiling or wall-1” unthreaded pipe exposed
Floor-2” unthreaded pipe exposed
How deep must gas lines be buried in a commercial installation?
24”
What is the first thing that must be determined prior to sizing a gas line?
Longest run (total furthest distance)
Pressure taken in a gas line with only the pilot burning is what type of test?
Standing pressure test
Pressure taken in a gas line with the appliances main burner operating is what type of test?
Operating pressure test
What is the minimum size face on a test gauge?
3” in diameter
Maximum working pressure of propane in a single family dwelling?
2 psig
Gas law that states the pressure will increase, volume will decrease if the temperature remains constant?
Boyles Law
Gas law that states if the temperature increases and the volume increases, the pressure will remain constant?
Charles Law
Two ways of removing water from natural gas?
Adsorption and absorption
Who is responsible for setting gas line pressures inside or outside of a building?
The installer
Define matter?
Anything that has mass and occupies space
What are 2 factors that affect the state in which matter exists?
Pressure and temperature
What type of heat is the energy absorbed or released when a substance undergoes a phase change?
Latent heat
When you say that liquid propane is lighter than water, you are referring to its?
Relative density
What is used to allow a single wall vent connector to pass through a combustible wall or partition?
A ventilated metal thimble
Clearance to combustibles for “C” vent?
6”
When a chimney liner is used, how much must the tables be derated?
20%
What type of venting is used on a high efficient oil burning appliance?
Type L
What do you call support hangers for vertical pipe?
Riser clamps
What is the function of pipe dope?
Lubricant
What is the maximum volume of gas released from a vent?
Natural gas
Propane
Natural gas-2.5 cu.ft
Propane-1cu.ft
How are gaskets for grooved joints identified?
By color
What can happen if a malleable iron fitting has been over tightened onto a carbon iron pipe?
Creeping
