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Level 3 - Gas Exam 3 > Review packages > Flashcards

Review packages Flashcards

1
Q

State the chemical abbreviations for propane and natural gas?

A

C3H8

CH4

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2
Q

What are the ignition temperatures for propane and natural gas?

A

1300F for natural gas

920F for propane

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3
Q

List the specific gravity for natural gas vapour and propane vapour?

A

natural gas - 0.6

propane vapour - 1.5

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4
Q

What is the specific weight of liquid propane?

A

0.51

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5
Q

What are the upper and lower limits of flammability for natural and propane gas?

A

2.4-9.5% propane

4-14% natural gas

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6
Q

What are the maximum flame temperatures for natural and propane gas?

A

3600F both

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7
Q

List the atmospheric boiling temperatures for natural and propane gas?

A
  • 44F propane

- 260F natural gas

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8
Q

What are the expansion ratios for natural and propane liquid when they change to gas?

A

1: 600 natural gas
1: 270 propane

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9
Q

What are the flame speeds of natural and propane gas?

A

25 in/sec - natural

32 in/sec - propane

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10
Q

what is the calorific value (heat content) of natural and propane gas?

btu/cubic foot:

btu/cubic meter:

A

btu/cubic foot: 1000btu/2520btu

btu/cubic meter: 33,100/88275

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11
Q

What number would be used to convert BTU’s to kW?

A

0.000293

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12
Q

How many btus equal one kilowatt?

A

3412

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13
Q

How many times larger is a cubic meter than a cubic foot?

A

35.31

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14
Q

How many times larger is the calorific value of a cubic meter than a cubic foot using the same gas?

A

35.31

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15
Q

What is the maximum pressure for low pressure gas? IN (psi. and inches water column)?

A

14’’ wc

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16
Q

An appliance is considered high input when it exceeds what input?

A

400,000btu/h

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17
Q

How many cubic feet of combustion air are required by a hydrocarbon fuel for each 1000 Btu’s of input?

Excess air:

Dilution air:

Total air:

A

excess = 5

dilution = 15

total = 30

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18
Q

List the products of combustion of natural gas?

A

CO2, H2O, N2, Heat, Light

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19
Q

Is a 2psig system considered high pressure?

A

no

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20
Q

An appliance has a rating of 283,000 btus, and runs on propane. How long would it take to burn 1,865 ft3 of fuel?

A

2520 x 1865 = 4,699,800 / 283,000 = 16.6

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21
Q

Define BTU

A

British thermal unit - amount of energy to raise 1lb of water 1 degree Fahrenheit

22
Q

What are the percentages of nitrogen and oxygen found in air?

A

20% oxygen

80% nitrogen

23
Q

What is the air/gas ratio required to achieve complete combustion of natural gas and propane?

A

10: 1 - for CH4
25: 1 for C3H8

24
Q

Explain the term primary air, with reference to an atmospheric burner?

A

air supplied with mixed fuel before ignition

25
Q

What is the term used to describe the additional air supplied to the combustion chamber of a gas appliance to ensure complete combustion?

A

excess air

26
Q

What is the purpose of dilution air?

A

reduce velocity of flue gases

27
Q

A gas appliance is considered to be high input when it exceeds what input?

A

400,000btu

28
Q

What are the pressure limitations of a class “b” license?

A

no pressure limit

29
Q

What is the name of the odorant used in natural gas to give it a distinct smell?

A

mercaptin

30
Q

1kw = _______btu’s

A

3412

31
Q

1m3 = ____ft3

A

35.31

32
Q

1psi = _____ inches water column

A

28”

33
Q

1 psi = ____ feet of head

A

2.31

34
Q

1 psi = ___ ounces per square inch

A

16

35
Q

An appliance burns 400 cubic meters of natural gas. How many cubic feet is this?

A

400 x 35.31 = 14,124 cu ft

36
Q

1000btu’s = ____kw

A

0.293kw

37
Q

Define calorific value

A

amount of heat released during combustion

38
Q

State the calorific value of natural gas in the four different ways we may need to refer to it?

A
  1. btu/ft3
  2. btu/m3
  3. kw/ft3
  4. kw/m3
39
Q

What is standard pressure in psi?

A

101.235psi

40
Q

What is standard temperature?

A

60F

41
Q

What is the manifold pressure for propane and natural gas?

A

propane = 11” w.c

natural gas = 3.5” w.c

42
Q

When converting propane to natural gas what must you do to the orifice and pressure?

A

increase orifice size and reduce pressure

43
Q

doubling the diameter _______

A

increased by 4 times

44
Q

Name the four parts of the regulator

A
  1. measuring element
  2. restricting element
  3. loading element
  4. vent opening
45
Q

How does a direct operating regulator close?

A

on downstream pressure

46
Q

What is the main difference between category 1 and 4 appliances?

A

category 1 is negative pressure

category 4 is positive pressure

47
Q

Which part of a cathode corrodes?

A

anode

48
Q

What is the main function of the pilot?

A

light the main burner

49
Q

When tubing enters or exits a concrete slab what must we do?

A

put a protective sleeve around it

50
Q

Can a homeowner always do his own work?

A

Not if there is a dwelling unit being rented out

Level 3 - Gas Exam 3 (4 decks)

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