Lvl.4 Final Gas Review Flashcards
LP Gases include propane and butane. True or False?
True
CV of natural gas is 0.293kw/ft3. True or False?
True
Calorific value or a butane/air mixture would be _______3200btu/ft
a) greater
b) equal
c) less than
c) less than because added air decreases CV
When LP gases are used, the appliance manifold pressure is usually 11” w.c. True or False?
True
What is commonly referred to as the silent killer?
CO
Processed natural gas with all the heavier hydrocarbons removed is sometimes referred to as?
a) wet gas
b) dry gas
c) sour gas
d) sweet gas
b
“Air required for satisfactory combustion of gas, including excess air”
a) combustion air
b) total air
c) ventilation air
d) dilution air
a
“Mechanical draft produced by a device downstream from the combustion zone of an appliance”
a) induced
b) forced
c) assisted
d) non-natural
a)
“A burner in which combustion air is supplied by a mechanical means such as a fan or blower at sufficient pressure to overcome the resistance of the burner and the appliance”
a) induced draft
b) forced draft
c) assisted draft
d) non-natural draft
b
When conflict exists between manufacturers instructions and the code book, whose instructions should the installer follow?
code book
Local gas inspector is responsible for ensuring appliance is in safe working order and complies to code regulations. True or False?
False
The _________ is responsible for making sure the home owner knows how to start, stop, operate appliance?
installer
Gas appliance replacement parts should
a) exceed original parts specs
b) meet or exceed original part spec
c) never meet or exceed
b
Installation of a used appliance
a) prohibited
b) requires approval by authority
c) inspected and approved by installer
c
Minimum service clearance for an appliance is 24”. True or False?
True
Hose connected to a portable appliance shall not be longer than
a) 40ft
b) 30ft
c) 25ft
d) 10ft
b
Test gauge shall have a minimum diameter of
a) 1”
b) 2”
c) 2.5”
d) 3”
d
Unless specified, a gravity warm air furnace high limit should not be set higher than
a) 550f
b) 450f
c) 350f
d) 250f
c
Unless specified, a forced air furnace high limit shall not be set higher than
a) 350f
b) 250f
c) 212f
d) 180f
b
Incinerators shall be equipped with
a) no barometric damper
b) single acting barometric
c) double acting barometric
b
Water heater, unless direct vented, shall not be installed in a
a) basement
b) carport
c) bathroom
d) mechanical room
c
Natural gas systems using copper tubing must be joined with forged brass nuts
a) true
b) false
a
Tubing used in gas piping systems must be supported
a) 6ft
b) 8ft
c) 12ft
a
B fitter may work on piping system upstream of gas company meter
a) true
b) false
b
In a commercial building, piping must be identified at intervals not exceeding
a) 20ft
b) 10ft
c) 6 ft
d) 3ft
a
SCH40 Black iron is limited to what pressure if using threaded joints?
a) 250psig
b) 125psig
c) 60psig
d) 20psig
125psig
Unless approved by authority, pipe joints must be welded if nominal pipe size exceeds
a) 1.5”
b) 2”
c) 2.5”
d) 3”
b
Copper or steel tubing may be
a) flared
b) brazed
c) flared or brazed
d) neither flared or brazed
c
Minimum length of dirt or drip pocket
a) 6”
b) 4”
c) 3”
d) 2”
c
Thread compound shall not be applied to
a) first thread
b) first two threads
c) first 6 threads
b
Joining polyethylene pipe to steel pipe requires the use of
a) approved transition fitting
b) quick-disconnect fitting
c) seismic relief
d) POL
a
Max diameter of a drip or dirt pocket
a) 6”
b) 4”
c) 3”
d) 2”
d
Underground piping must be buried a minimum of
a) 36”
b) 24”
c) 15”
c
Threaded pipe connections are allowed underground. True or False?
False
Piping, hose, and fittings used in a natural gas install shall be rated for a minimum 1.5 times the max operating pressure
a) true
b) false
True
Copper tubing installed in a residential building shall be identified by yellow bands or paint at intervals not exceeding
a) 6ft
b) 8ft
c) 12ft
d) 20ft
a
pressure relief for all portable propane cylinders is?
375PSIG
Portable propane cylinder must undergo physical examination every time it is filled. True or False?
True
Portable propane cylinder relief valve must be decertified or replaced every?
a) year
b) 2 years
c) 5 years
d) 10 years
d
Portable cylinder must not be filled more than ___% of its rated volume
80%
Portable cylinder must not be filled more than ___% of its rated weight
42%
Underground steel gas piping containing liquefied propane must be schedule
a) 40
b) 80
c) 20
b
Gas fitter may reduce amount of gas going into the appliance by moving the orifice spud closest to he burner nozzle. true or false?
true
When compared to an orifice with a k factor of .9, an orifice with a k factor of .8 will pass more gas?
true
Orifices are usually made of brass or aluminum. True or False?
True
Construction rental heaters are designed to be run on nat gas or propane and equipped with
a) fixed orifice
b) universal
c) adjustable
d) one
b
When calc input of appliance located after 5psig meter, gas fitter did not use PCF. Input will be
a) same as appliance firing rate
b) less then appliance firing rate
c) more than appliance firing rate
d) more or less
b
On a gas meter, which dial is used to check for leaks in the piping system?
a) consumption dial
b) indicating dial
c) proving dial
d) correction dial
c
When drilling orifices, it is recommended that they be initially drilled two sizes smaller than the anticipated required size
a) true
b) false
a
In order to size orifices on a gas fired appliance, it will be necessary for the gas fitter to know
a) ignition temp and model #
b) heating value or gas and model #
c) spec grav and diameter of pipe
d) spec grav and heating value
d
Insufficient combustion air will likely result in formation of
a) co2
b) co
c) condensation
d) carbonic acid
b
As amount of excess air increases, efficiency increases. true or false?
false
Limit of a forced air furnace is continually cycling on and off, gas fitter should check
a) see if filter is plugged
b) fan belt broken
c) fan speed low
d) all
d
Most important flue gas analysis check is for
a) co2 content
b) net stack temp
c) co content
d) draftp
c
Ultimate co2 percentage in natural gas is?
a) 4%
b) 10%
c) 12%
d) 14%
c
Net stack temp is
a) subtract ambient and actual stack
b) add actual stack and ambient
c) measure actual
a
When taking flue gas analysis for an appliance, where should the flue gas sample be taken
a) downstream draft control
b) upstream draft control
c) upstream heatX
d) at burner
b
Air that an atmospheric burner entrains through the Venturi is referred to as
a) primary air
b) secondary air
c) excess air
d) dilution air
a
Secondary air is
a) mixed with gas prior to ignition
b) preheated air added before ignition
c) mixed with gas at point of ignition
c
Burning propane gas with sufficient air will result in
a) n2, co, and o2
b) n2, co2, and o2
c) n2, co2, h2o
c
If a customer complains that the pilot flame is noisy, lifting, and blowing, you can suspect that
a) pilot orifice is too large
b) gas pressure too low
c) pilot line is clogged
d) gas pressure too high
d
Term incinerating, aerated, and target are all used to describe different pilots
a) true
b) false
true
Customer complains the pilot flame on his furnace often extinguishes when he opens door in basement. One way to minimize his problem is
a) install sediment trap
b) install filter in the gas line
c) install metal shield to deflect
c
If combustion air for a unit is supplied by a fan, fan must interlock with
a) burners
b) circulating air fan
c) high limit
d) vent roll out
a
Opening grills, louvers, screens shall be minimum ?
1/4”
Rectangular duct used for air combustion, ventilation, etc shall not be smaller than ?
3”
sizes are 3”-41”
Combustion air openings above 400,000btuh shall be located NOT LESS than 24” above finished outside grade
true
Continuous spillage from the draft could result in
a) overheating heat x causing limit open
b) safer and more efficient
c) co2
d) co
d
Products of combustion in a gas fired range are vented into the room
a) true
b) false
a
Sealed, separated, or direct vent appliances get all required air within the space
a) true
b) false
false
Type C vent requires ___ clearance from combustibles
6”
Allowing temp of flue gases to decrease will decrease potential for condensation
true
false
false
Barometric damper is designed to prevent spillage
a) true
b) false
false
Max temp of b vent is
a) 1500f
b) 1000f
c) 480f
d) 127f
c
Which type of vent is considered all-fuel vent
a) type a
b) type b
c) type bh
d) type c
a
Draft hood cannot be installed in a ceiling
true
false
true
Flue gases condense at approx
a) 470f
b) 250f
c) 127f
d) 72f
c
Minimum clearance from combustibles for a type A single wall chimney is
a) 2”
b) 6”
c) 9”
d) 18”
d
Vent pipes on automatic valves, diaphragm gas valves, pressure regulators, etc, shall not have an inside diameter less than
a) 1/4”
b) 3/8”
c) 1/2”
d) 5/8”
a
Positive shut off is required on all line pressure regulators when the system pressure exceeds
a) 1/2psig
b) 2psig
c0 5psig
a
Gas press reg should be sized according to
a) inlet pressure, piglet pressure, pipe size
b) inletP, outletP, flow rate
a
If bleed line of a diaphragm gas valve is plugged, the gas valve will
a) open faster
b) open slower
c) remain closed
c
Natural gas pressure regulator equipped with leak limiter will restrict the escape of gas to approx
a) 2.5ft/hr
b) 2ft/hr
c) 2%
a
Solenoid gas valves with manual opening devices are:
a) highly recommended
b) not allowed
c) restricted to propane fired gas installs
b
In electrical the hot wire is considered what colour
black
When an electrical switch is opened
a) power travels to the load
b) power to the load is interrupted
c) power to load is reversed
b
Staple shorting across the thermostat wiring could cause
a) appliance to run continuously
b) transformer to burn out
c) blower motor to stop working
d) burner to overfire
a
Ohms law states the current in an electrical circuit is directly proportional to the voltage ad inversely proportional to resistance
true
In North America the alternating current operates at
a) 120 cycles per second
b) 60 cycles per second
c) 40 cycles per second
b
Short circuit means hot wire is touching something that conducts electricity. True or False?
True
if the heat anticipator is set too high, the temperature in the room may become warmer than desired. True or False?
True
How water boiler uses a relay to
a) start and stop 120v pump with 24v switch
b) start and stop 25v pump with 120v switch
a
Spill switch is usually located at
a) outlet or fas valve
b) next to control module
c) discharge of draft diverter
c
Electrically operated vent dampers are connected in parallel to the gas valve
a) true
b) false
false
In a mv system, the distance from the gas valve to the thermostat should be limited to
a) 100ft
b) 75ft
c) 50ft
d) 30ft
d
If a thermostat on a mv system is equipped with a heat anticipator, the meter reading at the thermostat contacts of a gas valve should indicate a reading of
a) not more than 50mv
b) not less than 50mv
c) not more than 110mv
c
Standard thermocouple should produce a closed circuit test of approx
a) 25 to 40mv
b) 10 to 15mv
c) 9 to 10 mv
d) 2 to 5 mv
b
What is max flame failure response time of thermocouple?
a) 4 seconds
b) 10 sec
c) 60sec
d) 90 sec
d
Drop out point of a standard thermocouple should be
a) 25 to 30mv
b) 15 to 17mv
c) 9 to 10mv
d) 2 to 5mv
d
Numbers on the scale of the thermostat heat anticipator relate to
a) degrees when recalibrating stat
b) required differential below set point
c) required differential above set point
d) current draw of the control circuit of the appliance
d
On a 24v ac system, the safety shut off valve receives power from
a) transformer
b) thermopile
c) thermocouple
d) flame safeguard
c
A thermostat should be wired in series with the automatic gas valve
a) true
b) false
true
Which of the following is normally open
a) high limit
b) fan switch
c) low water cut off
d) solenoid gas valve
b
When using a combination high limit control on a forced warm air furnace, the high limit shares the bimetallic sensing device with
a) thermostat
b) safety shut off
c) pilot solenoid gas valve
d) fan switch
d
Electrical permit is required before installing or repairing electrical equipment
a) true
b) false
true
Inspection of electrical work is required before any portion of the completed work is concealed
a) true
b) false
true
Max voltage to ground for single family dwelling unit is
a) 240vac
b) 150vac
c) 120vac
b
It is permissible to use unqualified worker to perform electrical work without supervision
a) true
b) false
false
Minimum head room between receptacle and gas meter is
a) 1.5m
b) 2m
c) 1m
c
Flexible cord cannot be used to plug in a furnace permanently
true
false
true
Motor disconnect shall be installed
a) within 9m of furnace
b) within 9m and within sigh of furnace
c) within 3m and sight
b
When can a used furnace be installed
a) never
b) when inspected and found safe by installing gas fitter
b
Properly sized unit heater installed, but complaints of insufficient heat prevail
a) clock it to see if it is underfired
b) slow down fan speed
c) adjust plenum switch
d) seal all cracks in building
a
Porous refractory such as ceramic acts as the radiating surface of the burner in an infrared heater
a) true
b) false
true
Max input to a top burner on a gas range is adjusted by
a) adjusting primary air
b) adjusting cap orifice
b
High limit on a forced hot water boiler should not be higher than
a) 250f
b) 200f
c) 180f
d) 140f
