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108 Cards in this Set
- Front
- Back
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A non positive vent appliance over 83% efficient is what category appliance |
Cat 2 |
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A positive vent appliance under 83% efficient is what category appliance |
Cat 3 |
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A positive vent above 83% efficient is a cat ______ appliance? |
Category 4 |
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A non positive vent appliance operating at below 83% efficient is a cat _____ appliance |
Cat 1 |
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What sizes are transmission pipe lines for Nat gas |
20-42" pipe |
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What are the pressure ranges found in natural gas transmission pipe lines. |
300-1500 PSIG |
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What pressure does the utility operate on a LOW PRESSURE gas system |
8-14" water column |
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What is the INTERMEDIATE PRESSURE on a natural gas system |
2-80 psi G |
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What pressure is downstream of the service regulator in a nat gas system |
7" water column |
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What is sour gas? |
Gas with sulfer in it (creates acid rain) |
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Define atmospheric burner |
A natural draft burner |
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What's the conversion factor from WC to PSI? |
x28 |
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What is a dirt pocket and where is it in the system |
A spot in piping where dirt collects and can be removed
Installed in low points in the system |
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Define B.t.u |
British thermal unit 1 btu = amount to raise 1 lb of water 1°F |
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Chemical formula for natural gas |
CH4 |
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Chemical formula for propane gas |
C3H8 |
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Another word for calorific value |
Heat content |
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What's the Major composition of Nat gas? |
Methane |
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Define calorific value |
The amount of energy released when a given amount of fuel gas is burned |
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Natural gas can be classified as ______. Composed of _________ and ________ |
A hydrocarbon Hydrogen and carbon |
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What state is propane transported and sold in and why |
Liquid form. Takes up less space |
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What's the purpose of oderants in gaseous fuel |
So it can be detected |
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What is the oderant normally added to gas? |
Mercaptan |
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How much mercaptan is in a cubic foot of gas. |
1 ft cubed for 1ft cubed of gas |
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When is specific gravity of a fuel gas important |
Checking fir gas leaks Calculating flow of gas systems Sizing orifices |
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What's the specific gravity of natural gas. And is it lighter or heavier then air |
0.55 Lighter then air |
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Will Nat gas rise or fall when introduced to air? |
Rise -. It's lighter then air |
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What's the specific gravity for propane(c3h8) gas. Is it lighter or heavier then air |
1.52 Heavier |
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Expansion factor from liquid to gas -propane -nat gas |
Pro- 1:270 Nat- 1:600 |
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Propane containers are only filled with how much liquid |
80% |
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Boiling point of propane at atmospheric pressure |
-44°F |
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Boiling point of Nat gas at atmospheric pressure |
-260°F |
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1ft cubed of CH4 will perfectly combust and release ______ BTUs |
1000 |
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1 ft ³ of C3H8 releases how many BTUs when burned perfectly |
2500 BTUs |
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What does UEL stand for |
Upper explosive limit |
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What is L.E.L |
Lower explosive limits |
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What are the byproducts of incomplete combustion |
Carbon monoxide- CO water vapor Hydrogen Nitrogen Aldyhides Soot |
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What are the byproducts of complete combustion |
Carbon dioxide (CO2) Heat Water vapor |
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What is the byproduct that has safety issues found in flue gasses connected to a natural gas appliance |
Carbon monoxide C.O aldyhides |
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What does LPG mean |
Liquid petroleum gas |
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What state is propane at atmospheric pressure in the summer |
Gas |
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What is the Ultimate CO2 percentage during natural gas combustion taken from flue gas samples |
11.8% |
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Ultimate CO2 in propane gas burning is |
13.8% |
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What's the name of air that's used in perfect combustion |
Combustion air |
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What are the 2 parts of air consumed in perfect combustion |
Primary and secondary air |
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Where is primary air found entering an atmospheric burner |
Upstream of the point of ignition |
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Where is the secondary air found in an atmospheric burner |
Downstream of the point of ignition. |
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What are the limitations of a b fitter |
Can work at a 400000 btu max |
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What is the perpous of of excess air in a nat draft burner |
To supply extra air to the burn box if needed for combustion |
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Where is excess air found during combustion in a natural draft burner |
Combustion zone |
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Appliances with a draft hood will introduce ______ air when leaving the appliance |
Dilusion air |
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For every 15 feet cubes of dilusion air that enter the appliance venting system a volume of approx ______ BTUs has been produced by the burner |
1000 |
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Give an example of some corrosive substances that would cause premature failure |
Paints Glues Chlorine/ bleach Freon type refrigerants |
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What percent of natural gas to air mixture produces the fastest flame speed? |
10% gas to 90% air |
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What percentage of Propane gas to air mixture produces the fastest flame speed? |
6% L.P.G to 94% air |
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Give some examples of causes if an appliance produces carbon monoxide |
Lack of air or Too much air changes the ignition temperature Flame impingement Cracked heat exchanger Flue blocked / back draft
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What does the acronym C.G.I stand for in the gas industry ? |
Combustible gas indicators |
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What are the major constituents if air and their % make up? |
Oxygen 20% Nitrogen 80% |
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Which component or constituent is the key players in the combustion of a fuel? |
Air / O2 |
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Which part of air contributes nothing to the process of the combustion? |
Nitrogen |
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What effect may air have on the efficiency of the appliance? |
Too much or not enough causes flame to burn colder pulling the heat out- less efficient |
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Define specific gravity of a gas |
Comparison between the weight of a gas and the weight of air |
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What is the purpose of a burner orifice? |
Makes sure the proper amount of air and gas mixture thru Proper velocity of fuel to go thru |
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What is the normal valve position of a gas pressure regulator? |
Open |
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Name the dynamic component elements comprising of the gas pressure regulator |
Loading element(or spring) Valve plug Diaphragm |
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What is the purpose of the vent on the body of the gas regulator? |
Allows the reg to breathe during normal operation |
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What is the opening force in a gas regulator? |
The spring |
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What closes the gas regulator? |
The pressure downstream of the regulator has more force then the spring so it closes |
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When the gas regulator is in close position how will it open? |
Reduced pressure Allows spring to push back |
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What is the purpose of the regulator |
Maintain a constant downstream gas pressure |
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If a regulator diaphragm should rupture how can it be serviced |
Turn off gas upstream Open Fix or replace regulator
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What is the typical pressure downstream of the regulator? |
7" water collum |
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What does the term D.M.S stand for? |
Drill machine size |
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what changes should be made to the appliance when switching from natural gas to propane? |
Smaller orifice More manifold pressure Regulators change Change rating plate |
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What info should be left with the appliance once a change from pro to Nat gas has been made? |
New rating plate |
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What is the typical natural gas manifold pressure on the appliance? |
3.5 wc |
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What's the typical natural gas pressure between the meter and the appliance? |
7inch wc |
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What is the typical propane gas manifold pressure ? |
11 wc |
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What's the typical propane gas supply pressure from the meter to the appliances |
11-14 inch water collum |
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Describe the difference between c and b venting materials |
C = single wall vent B= double wall vent |
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What are the clearances for c and b venting? |
B= 1-2 inch c = 6 inch |
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What is the maximum rated temp for flue gasses in B vent? |
470 degrees F |
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What is the typical range for temps for flue gases exiting a flue collar off a cat 1 appliance? |
300-350 degrees F |
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Where is BH venting used |
Used for higher efficiency appliances |
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What materials are found in BH venting |
Stainless steel Plastic - system 636 |
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What are max temps for BH venting |
Steel - 570 Plastics 65-100 |
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What's another term used for c vent |
Single wall vent |
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What materials are in type L vent |
Inner stainless Insulation Outer galvenized |
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Max temps for type L vent |
570 degrees Fahrenheit |
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How are metal venting systems listed as certified to operate on a cat 4 Appliance |
must be BH stainless venting |
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What materials consist in BH venting |
Double wall Stainless Plastic |
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BW venting is specifically designed and certified for what appliance type? |
Recessed wall furnace |
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What are the rating and installation requirements for an A venting system? |
1000-1400 degrees Fahrenheit Insulated metal or brick or concrete |
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Define natural draft fired appliance |
Negative pressure that drafts naturally |
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Define fan assisted appliance |
Higher efficiency Uses a fan to pull or push air in Positive pressure |
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Define fan assist burner |
Assists air into the combustion zone at the bottom, at the burner |
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What is a forced draft burner / power burner |
Fan at burner to blow air into burnbox Positive pressure |
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Define static pressure in a gas system |
Pressurized gas that isn't moving in the line |
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Define working pressure in a gas system |
Gas flow of proper operation |
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Define pressure drop on a gas system |
Pressure drops between gas valve and the last appliance Due to friction loss, bends, and length of pipe
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Define byproducts of combustion |
End products of gas after combustion |
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Define combustion air |
Air used for complete combustion |
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Define depressurization |
Reduced pressure in the combustion air zone Need fresh combustion air inlet to create a negative pressure to vent properly |
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Define heat value |
Amount of energy used for combustion of a given volume of fuel |
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What 2 typical states can L.P gas exist in |
Liquid and gas |
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List the 3 types of air that make up total combustion air |
Delusion air Excess air Combustion air |
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Ignition temp for methane |
1300 |
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Ignition temp for propane |
900 |
