Gas Install Chpt. 5&6 Flashcards
U-tube manometers (water-filled) usually read very low gas pressures and express them in
inch of water column
Why would a mercury manometer be used instead of a water manometer?
more compact, read higher pressure
Name the parts of the regulator which correspond to the previous question.
(Restrict) Valve seat, orficie, (sensing) diaphragm, (loading) regulator spring test
what is the stated advantage of using higher gas piping pressures than that required by the appliance?
smaller pipe
turning the adjusting screw clockwise would ______ the regulator outlet pressure
increase
what are five factors which must be considered when choosing a gas pressure regulator
1)rate of flow 2)type of gas 3)inlet gas pressure 4)outlet gas pressure 5)size of gas pipe, pipe sizing an inlet and outlet of regulator
a diaphragm gas valve uses _______ as the primary force to open or close the valve
gas pressure
when the components of a gas valve-train are all contained within one valve, it is known as a _______
combination gas valve
if a pilot only comes on when there is a call for heat, it is called a/an ________ pilot
direct ignition
when the reset button is pushed, gas flows to both main and pilot burners
false
the movement of _______ causes an electrical current to flow in a circuit
electrons
the device which uses heat to create electricity is called a _______ or ________
thermocouple, thermopile
a spark igniter for a barbecue is an example of what type of electricity
pizo
in an AC (alternating current) wave form, both ______ and ______ buildup, peak, reverse direction, then build up and peak in the opposite direction, before returning to zero.
voltage, current
where is three-phase electricity used
commercial and industrial applications
current generated in north America is at ___ cycles per second, or hertz
60
electrical pressure, know as EMF or electromotive force is measured in units called _____
volts
electrical resistance is measured in units called ______
ohms
what is the most important consideration when using an ohmmeter
power must be off, lock out tag out
100%
the term wattage or watts is an expression of electrical ______; watts equals ______ multiplied by ______
power, volts, amps
______ circuits have only one path for current to follow; ______ circuits have multiple paths
series, parallel
how is the total resistance in a series circuit calculated?
R=E/I total sum added up
correct polarity of the test leads must be observed when using an ammeter with DC.
true
the moving part within a switch is called a ____; the contact it makes is called a _____.
pull, throw
the simplest device used to prevent excessive current from damaging circuits is called a _____
fuse
what makes the operation of a circuit breaker from that of a fuse
you can reset a circuit breaker
by what electrical processes does a step-up or a step-down transformer operate?
electromagnetic induction
what two electrical components are found within a relay
switch, load
what is the name of the wiring diagram which shows the electrical components of a gas appliance much like they appear behind the service door of the appliance
schematic
what are three advantages of a ladder diagram over a schematic diagram
make it easy to tell which are series and parallel, easier to follow
as an overall safety precaution when working around live equipment, always assume that any wire could be ______
live
what do automatic gas valves usually employ as an actuator to make them open or close?
electromagnetic coil
a low-water cutoff would be classified as a ________ control
safety limit
a thermostat would be classified as a/an _______ control
operating
if a boiler needs flowing water in order for it to operate, this could be proven electrically by using a ________
flow switch
a solenoid gas valve would be an example of a/an _______
actuator
most state, local or provincial codes allow a maximum of ______ seconds for a thermocouple and power unit to drop out
90
what is the device called which is found within a thermostat, and is used to minimize thermal lag?
anticipator
what is th function of a direct-acting aquastat?
opens or breaks contact on rise in temperature
on what types of systems are pressuretrols normally found
steam heating system
a probe-type low water cutoff uses the _______ of the liquid to complete a circuit
conductivity
what is the maximum flame failure response time for a high volume (over 400,000 Btuh) appliance?
10 seconds or less
a difference in ______ between the hot and cold junctions of a thermocouple or thermopile will generate electricity
temprature
the pilot burner flame must envelope _______ inch(es) of the hot junction of a thermocouple or thermopile
3/8 to 1/2
why are photocells not used to monito gas flames?
gas flame does not produce enough visible light
the earliest flame-rod systems used a flame’s ________ to complete an electrical circuit
conductivity
an open circuit test of a thermocouple should produce ______ to _____ millivolts: a closed circuit test should roughly one-half of these voltages
20-30 mv
most nuisance shutdowns in millivolt systems are a result of excessive _________ in the circuit
resistance
when a flashlight battery goes dead, it is because the ______ has been used up
zinc
_______ corrode: cathodes do not
anodes
one method of preventing underground steel piping from corrosion is to install a/an ________ onto the pipe
sacrificial anode
an audible and visual electronic test to find flaws in a coated pipe is termed a _____ test
jeep
cathodic protection of underground piping should be supervised by specialist familiar with that type of work.
true
name the two different types of domestic hot water heaters, and give a brief description of each type.
instantaneous, storage type
what device in the tank of a domestic hot water heater ensures that cold water entering the tank does not immediately leave through the hot outlet?
dip tube
the _______ slows the flue gases as they pass upward through the heater, increasing heat transfer and efficiency
flu baffle
the specific gravity (relative density) of propane and gasoline vapors is _____ than air
heavier
the air passages through a gravity furnace must be _______ than those of a forced air model
larger
forced air furnaces use a ______ to move the heated air to the rooms
blower
the three types of furnaces, as classified by the direction of air flow across the heat exchanger, are _______, ______ and _______
up flow, down flow, and horizontal
how is the combustion efficiency usually determined?
by analyzing componet percentages at the flu gas
a ______ boiler combustion control reacts to temperature; the _____ boiler combustion control reacts to pressure
hot water, steam
which type of boiler can be assembled in place, and added to if necessary?
cast iron sectional
what are the materials from which most hot water boilers are constructed?
steel or cast iron
usually, small water volume (low mass) boilers require the ________ to operate before allowing the burner to fire
circulating pump
pressure relief valves for residential and small commercial boilers are usually preset at ___ psig (____kPa)
30 psig
where might a journey worker find a start-up instructions for a new boiler?
installation manual
what type of valve on a gas range allows the use of either propane or natural gas?
universal orifice
what is the maximum cooking time for an oven when set to timer mode?
20
what do soft yellow flames at the top burner indicate
to fuel rich
what is another name for a glo-plug which is used to ight a gas oven burner electrically?
carborundun
an oriental range uses a _____ as the cooking bowl (pot)
wok
what type of heat is used with broilers?
radiant
why are commercial kitchens kept at a slightly negative air pressure
air moves from the dinning room prevent odors
to get even more water out of the clothes (after washing and before drying) commercial laundries often use a high-speed spin appliance called a/an ______
extractor
what is the maximum time a dryer will spark to try to establish a flame?
10 seconds
how many Btuh is equal to q candle power?
65 Btuh
