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211 Cards in this Set
- Front
- Back
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boiling point of Natural gas
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- 258
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Hydrocarbon are made up of
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hydrogen and carbon atoms
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Secondary air alow to achive the
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complete combustion of the fuel
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Excess air is the air supply above the
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theoretical air
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a sustance consisting of carbon and hydrogen is a
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hydrocarbon
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The weight of the gas as compared to the weight of an equal volume of air at standard conditions is
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Specific gravity
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The cubic feet or cubic meter of air required to burn one cubic foot of gas is:
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the air gas ratio
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The specific gravity of natural gas is
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0.6
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The specific gravity of propane is
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1.56
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A flame where there is no premixing of the fuel with the required air for combustion is know as
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yellow flame
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The blu flame is
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Blu in color, small, non luminous and has a higher temperature
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An other name for yellow flame is
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Luminous flame
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An other name for blu flame is
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Bunsen flame
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The yellow flame is
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bright, luminous and yellow in color
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The blu flame is a resul of
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some premixing of the fuel with the required air for combustion
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1 cu.ft. of air will release
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100 Btu of heat from any fuel
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Yellow flames are sometimes found on
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low input pilot burners used with gas ranges
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The maximun input for mini pilot is
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500 Btu
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The name of the combustion air that is mixed with gas in a burner before leaving the port
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primary air
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The name of the combustion air that mixes with the burning gas-primary air mixture in the flame zone
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secoundary air
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The amount of air above the ideal or theoretical to ensure the complete combustion of the fuel
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excess air
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Heat is a form of
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Energy
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The four forms of energy that you can convert into heat energy are:
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Mechanical, Chemical, Light and Electrical
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Temperature indicates the average __________ of the molecules in a sustance.
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velocity
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The two scales commonly use to measure temperature are:
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Fahrenheit and Celsius
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Btu is:
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The amount of heat required to rise one pound of water one degree Fahrenheit
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Another definition of BTU is
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The amount of heat energy that will raise 55 Cu.ft. of air 1 F
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As the temperature of any sustance increase, the molecules which make up the sustance vibrate:
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faster
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The movement of heat from one place to another between two substances or within a substance is know as
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Heat transfer
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The tree ways heat is transferred are called:
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Conduction, radiation and convertion
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Materials that are good at moving heat by conduction are called:
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Conductors
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To achive the combustion or burning of a fuel, three components must be present:
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Heat, fuel and Oxigen
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The composition of natural gas is
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89-90% of Methane
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The products of the incomplete combustion are:
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Carbon monoxide, aldehydes and soot
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Aldehydes have:
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sharp and penetrating odor
Irritate nose are accompanied by CO will kill |
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Soot is
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black in color
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Natural gas is formed by
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the descomposition of organic matters under high temperature and pressure
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the boiling point of propane is
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-44 F
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Carbon monoxide
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Is odorless
Is colorless has not taste it will kill |
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Natural gas is
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Odorless
Color less Has not teste Non toxic |
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The composition of the air is
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20% Oxigen 80% Nitrogen
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Gas air mix determines
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Burning speed
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burning speed which affects
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Flame stability
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Combustion is
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The rapid combination of a fuel with oxigen resulting in the release of heat
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the quemical structure of methane is
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CH4
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The quemical sructure of propane is
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C3H8
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The required air/gas ratio for natural gas is
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10
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The required air/gas ratio for propane is
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23.5
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The heating value for natural gas is
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1000 Btu/cu.ft.
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The heating value for propane is
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2500 Btu/cu.ft.
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The flame temperature for natural gas is
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3500 F
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The flame temperature for propane is
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3600 F
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The flame speed for natural gas is
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2 Ft/seg
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The flame speed for propane is
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2.7 Ft/seg
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The ignition temperature for natural gas is
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1100 F
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The ignition temperature for propane is
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1000 F
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The lower limit of flamability for NG is
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4
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The lower limit of flamability for LP is
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2
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The upper limit of flamability for NG is
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14
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The upper limit of flamability for LP is
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10
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Another name for heat value or heat contet is
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Calorific
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The maximun obtainable flame temperature can only be achive at_____________ where excess air or fuel will not provide the material to absorb the heat of combustion
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perfect combustion or 100% theoretical air
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Where air is used as the source of oxigen, the ________ that is in the air does not enter in the combustion reaction
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Nitrogen
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Nitrogen is ________ and pass through the _____________ absorbing ___________from the combustion reaction.
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inert
combustion process heat |
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Burning speed is the rate of speed the flame travels through the
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gas-air mixture
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To achive a ___________ the flame speed must equal to the _____________ of the air/gas mixture issuing from the burner port
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stable flame condition
velocity |
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In the combustion reaction, one part of NG combines with two parts of oxigen to form:
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one part of carbon dioxide, one part of water vapor and heat
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Burning speed is sometimes referred to as the
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flame speed
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A safety precaution is that NG must be ___________
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detectable by smell
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The name of the odorant adds to the naturals gas is
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Mercaptan
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Natural gas will always be in a
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gaseous state
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The pressure of a gas is:
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The force of the molecules being exerted on the walls of a container
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The natural gas flow rate of an appliance is
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Name plate input(Btu)/heating value
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The property of a gas to expand uniformly and indefinitely is called
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diffusion
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Boyle's law state
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The volume of the gas varies inversely to the pressure at temperature constant
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Charles' law I state
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The pressure of a gas varies directly with the temperature provided that the volume of the gas remains constant
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Charles' law II state
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the volume of a gas varies directly with the temperature provide that the pressure of the gas remains constant
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the pressure of a gas mesurement from the perfect or complete vacum is
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Absolute pressure
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A pressure measurement taken by a pressure gauge in wich zero is calibrate at local atmosferic pressure is:
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Gauge pressure
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Refers to the pressure in a gas line in which no flow is taken place
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Static place
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Is another name for static pressure in which the gas line is locked up between the gas meter and the burner
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Lock up pressure
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Refers to the pressure in a gas line which flow is taken place within the gas line
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Working pressure
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Flow is the movement of a gas from_____________area to a _____________ area.
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high pressure
low pressure |
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The expression Cubic feet per hour is a measure of the:
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Flow rate
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There is resistance to the flow of a gas just as there is resistance to the flow of_______
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electricity
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The molecules lose a small amount of their total energy by being __________ and _________ along the sides of the pipe
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rubbed and scrubbed
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Pressure drop in gas line is equal to
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working pressure at the gas meter outlet minus working pressure at appliance
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The resistence to the flow depends on:
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Lenghth of run of gas pipe
The size of the gas pipe Number of fittings The size of the flow rate The specific gravity of the gas |
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Any pressure below the atmosferic pressure is considered:
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Vacuum
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Atmospheric pressure is iqual to
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14.7 psi
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1 psi=
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28 in.wc or 16 osi
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The pressure at the outlet of the gas meter is the
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House line pressure
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The pressure at the gas burner downstream of all control valves is the
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manifold pressure
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The working pressure at the meter outlet in a residential system is =
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6.5 inwc
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The standar manifold pressure is =
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3.5 inwc
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The maximum house line pressure =
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14 inwc
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The standart houseline pressure =
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7 inwc
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The two basic instruments used to measure gas pressure are:
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Bourdon tube pressure and water filled manometer.
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The general gas law is
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P1V1/T1 =P2T2/T2
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The absolute temperature in degrees Rankin is=
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460+t
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14.7 psi is the
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atmospheric pressure at the sea level
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The operation of the gas meter is based on the principle of ___________
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positive volumetric displacement of the gas
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The bellows or diaphragm meter is used for
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domestic and commercial applications
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The rotary meter is used only for :
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medium and large commercial applications
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Which are the basically two types of positive displacement gas meters
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Bellows or diaphragm and the rotary
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Record the gas consumption over a period of time for billing purposes
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Consumption dials
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It can be used to determine the applice input and to test the gas meter and downstream gas line for leak
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Test dial
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Before performace the meter cloking you should
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1- Turn OFF other equipments
2- Read manifold low rating plate |
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The clocking meter formula
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3600*HV*dial size*pressure factor/secounds per revolution
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The secound per revolution will be
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the average of five readings
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The meter should be
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protected by a guard
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The preferred meter location is
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outside
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All outside meters are
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temperature compensate
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Meter should not be located
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Under combustible stairways
In unventilated or inaccesible locations In an area not closer than 3 feet from a source of ignition including furnaces and water heaters |
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The maximun concentration of CO in a gas appliances is
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400 ppm
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The two basic gas controls used on all furnaces are
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pressure regulators and gas valves
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When lowering the gas pressure in the manifold, turn the regulator adjusting screw counterclockwise to _______ the spring pressure on the diaphragm
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decrease
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The funtion of a gas pressure regulator is
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Mantain a constant downstream gas pressure
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The tree operating element in a gas regulator are
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1-The loading element (spring)
2- The measuring element(diaphragm) 3-The restrigting element (valve) |
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The loading element is
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The opening force
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The mesuring element
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sensed dowstream force
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The appliance regulator reduce the upstream house line pressure to
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the required dowstream manifold pressure
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The appliance regulator reduce pressure of 7 inwc to
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3.5 inwc manifold pressure
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The regulator that reduce the upstream gas service line presure in psi to inwc is the
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Service regulator
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The vent allow
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The regulator to breathe
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Cause the regulator open slowly and close normaly
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Surge arrester
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Allow equal limits of inhalation and escape of air from the upper diaphragm rupture
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leak limiting orifice
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Limits gas scape to safe limits should a diaphragm rupture
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Automatic safety vent limiting device
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Movement of the linkage, as actuated by the diaphragm, will open and close the valve
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The service regulator linkage
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Restric the gas flow through the regulator
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The service regulator orifice
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100% shut-off when the valve is closed preventing any gas flow through the orifice
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The service regulator valve seat
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The minimun required inlet pressure adjustment is ___ above the maximun adjustmen range of the spring
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1 inwc
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A high capacity type regulator are of the
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straight-thru-flow desing
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The low capacity type appliance regulator are designed to
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provide safe uniform gas to residential gas appliances
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The low capacity type appliance regulator that have a main burner and pilot load application are designed with a ____ stamping on the body
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P
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To size the gas presure regulator you need
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1-The inlet pressure
2-The required outlet pressure 3-The flow rate required by the appliance 4-The regulator orifice size |
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Gas flow out of it into a network of gathering lines that convey the gas to a central transmition line
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Gas well
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The gas is compressed, purified, measured and fed into the transmission line under very high pressure
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Compressor station
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In it the gas is measured, odourized and regulated
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City gate station
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It must be regulated down from extra high pressure to lower levels of pressure
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District regulating station
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The oulet pressure at the service regulator is usually set at ______ giving approximately ______ at the meter outlet
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7 in.wc 6.5 in.wc
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It is the gas line that conveys the gas from the main to the customer's premises it has the same pressure as that in the gas main.
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Gas service
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This is the main interior building line that supplies gas to the various appliances
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Gas supply line or building line
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This is the gas line running from the supply line over to an individual appliance
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Branch line
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It is that part of the branch line which drops down to the appliances
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Drop line
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It conveys the gas up to an appliance
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Riser
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Consists of a tee, nipple and cap located at the bottom of a drop line
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Drip or dirt pocket
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Pipe dope and pipe tape are applied only to the
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male thread of the fitting
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When using pipe dope or tape the ______________ threads are left free of any dope or tape
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first two
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The ends of all gas piping shall be
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reamed
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Gasket material for regulators and control valve must be made of some __________
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synthetic material
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Probibited piping practice are
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Bending gas pipe
Bushings, thread protectors or running threads Street elbows and tees Close nipples Gas lines to be used as an electrical ground |
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Limitation on the location of gas piping and tubing
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Chimneys
Coal chutes Warm air and ventilating ducts Elevator shafts Dumb waiters Stairwells |
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All gas piping running from one building to another will have a ________ at the point of exit from first building and one at the point of entry to the adjoining building
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Shut-off valve
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Gas piping of a size less than ____ cannot be concealed
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1/2 in
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All concealed piping and tubing must be
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tested and inspected in its final position prior to being concealed
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Underground piping and tubing must meet the following requirements
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All pipe joints must be welded
All joints or connections in copper tubing must be brazed The piping cannot be smaller than 1/2 in Cannot pass below foundations, walls or under buildings Must be wrapped with a corrosion resistant material |
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A manual valve, known as the ______ must be installed in every drop line or rise for lines greater than ______ or having a pressure greater than ______
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Drop valve, 1 in, 1/2 psi
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In commercial and industrial buildings the gas supply line is differentiated from other systems by
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being painted with a coat of highly visible yellow paint
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The smaller size of pipe that can be used indoors is
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1/2 in
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The gas line testing should be made:
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Before the appliances are connected
After the appliances are connected After gas has been turned on in to the system |
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Before the appliances are connected
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The gas line is isolated and is tested with air or inert gas. (CO2 or N2)
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After the appliances are connected
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meter dial test
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Once the meter dial test is comleted all appliance connestions control valves and others appliance piping components must be ___________ under normal operating pressure to ensure that they are ___________
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soap tested gas tight
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After gas has been turned On into the system
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Having the appliances shut off, the meter's test dial hand is marked as to its position the position should be hold for at least 10 min
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If a gas leak is indicated it can be found using
|
a soap and water solution
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After the gas line has been tested, it must be
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purged
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The line is always purged at the _________
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farthest appliance
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Branche lines are then purged
|
individually
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Gas lines 4" or larger that were air tested, cannot be purged unless
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an inert gas is used to separate the air from the gas
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Gas lines 4" or larger must be purged
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directly to the outdoors
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Maximum allowable pressure drop in a system with a pressure less than 7 in.wc
|
0.5 in.wc
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Maximum allowable pressure drop in a system with a pressure between 7 in.wc and 14 in.wc
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1.0 in.wc
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Maximum allowable pressure drop in a system with a pressure 2 psi and over
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30% of the supply pressure
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When a natural gas source is tapped by well, natural gas, being lighter than air and under pressure, will rise to the earth's surface without any additional force
|
T
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natural gas is 60% heavier than air
|
F
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What happens to the volume of a given weight of gas, if the temperature of the gas increased from 100 to 200 F , while the pressure on the gas remains constant
|
Increase
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Is permission required from the gas supplier to initially open or make connections to the gas service
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Yes pulling a permit
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What type of valve is normally place ahead of a gas regulator and meter
|
a 1/4 turn lubricated plug type valve place with locking wins
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State one of the funtions of a gas meter other than a measurement of consumption
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leak test
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The volume of any given weight of gas (confined gas) at a constant temperature is ______ proportional to the absolute pressure exerted on it
|
indirectly
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The piping material that is normally acceptable for use indoors in a gas piping system
|
Black steel schedule 40
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|
Tree corrotion-resistant coatings that may be allowed in some areas are
|
Extruded polyethylene
PVC resin Yellow jacket or approved paint |
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Pipe supports for 3/4 and 1" pipe should not more than
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8 feet apart
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Electrical circuits should not be grounded to gas piping systems
|
T
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What must be done upon completion of the roughing of a gas piping system and when is a witness test required
|
Conciel or burrier pipe
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Drawings and written instructions or specifications are always supplied for designing piping systems
|
F
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Explain how you would determine if a gas regulator is mantaining the correct pressure
|
Placing a water colum manometer downstrem of the regulator and running the appliance
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|
|
2.3 feet.wc are
|
1 psi
|
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The clearance between a roof top appliance and the edge of the roof is a minimum of
|
6 feet
|
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Drip pockets must be installed in a
|
no frost location
|
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All gas openings for future use should be _______ or ________
|
cap or plug
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Malleable bushings may be used to reduce size on a gas piping system provided the bushing reduces at least _____ pipe diameters. Steel bushings can reduce ____ pipe diameter
|
2 1
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It is considered necessary to protect the vent opening of a pressure regulator from, ice, sleet, etc
|
T
|
|
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Normally an appliance connected to a gas system should be equipped with a shut-off valve (except commercial kitchens and direct vent appliances0
|
T
|
|
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To increase the outlet pressure of a regulator, the adjusting screw must be turned counter-clockwise
|
F
|
|
|
Tubing joints underground shall be brazed with a material that melts at a minimun temperature of
|
1000 F
|
|
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After installation or servicing, what final test should be done on the appliance
|
Operating and safety control test, temperature rise, venting system
|
|
|
Natural draft max manifold pressure is _________
|
1 psi or 14 inwc
|
|
|
The atmospheric burner can be define as a burner which utilizes
|
the energy of the gas stream to induce air at atmospheric pressure to be mix with gas
|
|
|
Primary air going inside the burner by
|
a ventury design
|
|
|
The secondary air is mixing with the fuel by
|
convection
|
|
|
Aprooroximately ____% of the total air required for combustion is primary air
|
50
|
|
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The turndown range is betwen
|
40-100%
|
|
|
Theoretical ir is _____ primary air _______ secondary air
|
5 CF
5 CF |
|
|
The _______ or _______ is one witch has sufficient intensity to give flame stability
|
perfect flame or neutral flame
|
|
|
_________ and ________ are operating limits that are imposed on the burner
|
Flame lifting and flashback
|
|
|
Turndown ratio =
|
Max burner Btuh input/Min burner Btuh input
|
|
|
Flame lifting happen when
|
too much primay air is used
|
|
|
Flashback happen when
|
the air/gas mixture or flow velocity is less than the burning velocity
|
|
|
There are three types of gas orifices
|
Fixed
Adjustable Cap(or universal) |
