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UA Star Exam > Gas Install Chpt. 5&6 > Flashcards

Gas Install Chpt. 5&6 Flashcards

1
Q

U-tube manometers (water-filled) usually read very low gas pressures and express them in

A

inch of water column

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2
Q

Why would a mercury manometer be used instead of a water manometer?

A

more compact, read higher pressure

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3
Q

Name the parts of the regulator which correspond to the previous question.

A

(Restrict) Valve seat, orficie, (sensing) diaphragm, (loading) regulator spring test

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4
Q

what is the stated advantage of using higher gas piping pressures than that required by the appliance?

A

smaller pipe

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5
Q

turning the adjusting screw clockwise would ______ the regulator outlet pressure

A

increase

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6
Q

what are five factors which must be considered when choosing a gas pressure regulator

A

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

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7
Q

a diaphragm gas valve uses _______ as the primary force to open or close the valve

A

gas pressure

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8
Q

when the components of a gas valve-train are all contained within one valve, it is known as a _______

A

combination gas valve

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9
Q

if a pilot only comes on when there is a call for heat, it is called a/an ________ pilot

A

direct ignition

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10
Q

when the reset button is pushed, gas flows to both main and pilot burners

A

false

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11
Q

the movement of _______ causes an electrical current to flow in a circuit

A

electrons

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12
Q

the device which uses heat to create electricity is called a _______ or ________

A

thermocouple, thermopile

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13
Q

a spark igniter for a barbecue is an example of what type of electricity

A

pizo

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14
Q

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.

A

voltage, current

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15
Q

where is three-phase electricity used

A

commercial and industrial applications

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16
Q

current generated in north America is at ___ cycles per second, or hertz

A

60

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17
Q

electrical pressure, know as EMF or electromotive force is measured in units called _____

A

volts

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18
Q

electrical resistance is measured in units called ______

A

ohms

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19
Q

what is the most important consideration when using an ohmmeter

A

power must be off, lock out tag out

100%

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20
Q

the term wattage or watts is an expression of electrical ______; watts equals ______ multiplied by ______

A

power, volts, amps

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21
Q

______ circuits have only one path for current to follow; ______ circuits have multiple paths

A

series, parallel

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22
Q

how is the total resistance in a series circuit calculated?

A

R=E/I total sum added up

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23
Q

correct polarity of the test leads must be observed when using an ammeter with DC.

A

true

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24
Q

the moving part within a switch is called a ____; the contact it makes is called a _____.

A

pull, throw

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25
Q

the simplest device used to prevent excessive current from damaging circuits is called a _____

A

fuse

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26
Q

what makes the operation of a circuit breaker from that of a fuse

A

you can reset a circuit breaker

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27
Q

by what electrical processes does a step-up or a step-down transformer operate?

A

electromagnetic induction

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28
Q

what two electrical components are found within a relay

A

switch, load

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29
Q

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

A

schematic

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30
Q

what are three advantages of a ladder diagram over a schematic diagram

A

make it easy to tell which are series and parallel, easier to follow

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31
Q

as an overall safety precaution when working around live equipment, always assume that any wire could be ______

A

live

32
Q

what do automatic gas valves usually employ as an actuator to make them open or close?

A

electromagnetic coil

33
Q

a low-water cutoff would be classified as a ________ control

A

safety limit

34
Q

a thermostat would be classified as a/an _______ control

A

operating

35
Q

if a boiler needs flowing water in order for it to operate, this could be proven electrically by using a ________

A

flow switch

36
Q

a solenoid gas valve would be an example of a/an _______

A

actuator

37
Q

most state, local or provincial codes allow a maximum of ______ seconds for a thermocouple and power unit to drop out

A

90

38
Q

what is the device called which is found within a thermostat, and is used to minimize thermal lag?

A

anticipator

39
Q

what is th function of a direct-acting aquastat?

A

opens or breaks contact on rise in temperature

40
Q

on what types of systems are pressuretrols normally found

A

steam heating system

41
Q

a probe-type low water cutoff uses the _______ of the liquid to complete a circuit

A

conductivity

42
Q

what is the maximum flame failure response time for a high volume (over 400,000 Btuh) appliance?

A

10 seconds or less

43
Q

a difference in ______ between the hot and cold junctions of a thermocouple or thermopile will generate electricity

A

temprature

44
Q

the pilot burner flame must envelope _______ inch(es) of the hot junction of a thermocouple or thermopile

A

3/8 to 1/2

45
Q

why are photocells not used to monito gas flames?

A

gas flame does not produce enough visible light

46
Q

the earliest flame-rod systems used a flame’s ________ to complete an electrical circuit

A

conductivity

47
Q

an open circuit test of a thermocouple should produce ______ to _____ millivolts: a closed circuit test should roughly one-half of these voltages

A

20-30 mv

48
Q

most nuisance shutdowns in millivolt systems are a result of excessive _________ in the circuit

A

resistance

49
Q

when a flashlight battery goes dead, it is because the ______ has been used up

A

zinc

50
Q

_______ corrode: cathodes do not

A

anodes

51
Q

one method of preventing underground steel piping from corrosion is to install a/an ________ onto the pipe

A

sacrificial anode

52
Q

an audible and visual electronic test to find flaws in a coated pipe is termed a _____ test

A

jeep

53
Q

cathodic protection of underground piping should be supervised by specialist familiar with that type of work.

A

true

54
Q

name the two different types of domestic hot water heaters, and give a brief description of each type.

A

instantaneous, storage type

55
Q

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?

A

dip tube

56
Q

the _______ slows the flue gases as they pass upward through the heater, increasing heat transfer and efficiency

A

flu baffle

57
Q

the specific gravity (relative density) of propane and gasoline vapors is _____ than air

A

heavier

58
Q

the air passages through a gravity furnace must be _______ than those of a forced air model

A

larger

59
Q

forced air furnaces use a ______ to move the heated air to the rooms

A

blower

60
Q

the three types of furnaces, as classified by the direction of air flow across the heat exchanger, are _______, ______ and _______

A

up flow, down flow, and horizontal

61
Q

how is the combustion efficiency usually determined?

A

by analyzing componet percentages at the flu gas

62
Q

a ______ boiler combustion control reacts to temperature; the _____ boiler combustion control reacts to pressure

A

hot water, steam

63
Q

which type of boiler can be assembled in place, and added to if necessary?

A

cast iron sectional

64
Q

what are the materials from which most hot water boilers are constructed?

A

steel or cast iron

65
Q

usually, small water volume (low mass) boilers require the ________ to operate before allowing the burner to fire

A

circulating pump

66
Q

pressure relief valves for residential and small commercial boilers are usually preset at ___ psig (____kPa)

A

30 psig

67
Q

where might a journey worker find a start-up instructions for a new boiler?

A

installation manual

68
Q

what type of valve on a gas range allows the use of either propane or natural gas?

A

universal orifice

69
Q

what is the maximum cooking time for an oven when set to timer mode?

A

20

70
Q

what do soft yellow flames at the top burner indicate

A

to fuel rich

71
Q

what is another name for a glo-plug which is used to ight a gas oven burner electrically?

A

carborundun

72
Q

an oriental range uses a _____ as the cooking bowl (pot)

A

wok

73
Q

what type of heat is used with broilers?

A

radiant

74
Q

why are commercial kitchens kept at a slightly negative air pressure

A

air moves from the dinning room prevent odors

75
Q

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 ______

A

extractor

76
Q

what is the maximum time a dryer will spark to try to establish a flame?

A

10 seconds

77
Q

how many Btuh is equal to q candle power?

A

65 Btuh

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