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Plumbing Level 3 > E5: Select Gas Burners > Flashcards

E5: Select Gas Burners Flashcards

1
Q

Gas burners can be either?

A

Mechanical or Non-Mechanical

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2
Q

What determines the type of gas burner is used?

A

How the combustion air is supplied

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3
Q

What’s another name for Non-mechanical gas burner?

A

atmospheric burner

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4
Q

What do non-mechanical rely on for combustion air?

A

Atmospheric pressure

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5
Q

What is High Fire?

A

max firing rate of a burner

Is the max fuel input / heat output a burner can safely be operated at.

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6
Q

Low fire

A

min input of fuel required to keep a burner from flaming out

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7
Q

Modulation

A

Vary gas input / vary heat output to a process in order to match heat load requirement / sustain the desired temp

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8
Q

What is Turndown ratio? (TURNED DOWN FOR WHAT!)

A

ratio of the max fuel input : min fuel input rate for modulating burner.

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9
Q

What is the Turndown ratio used for?

A

To help determine how low a boiler can modulate before it turns off

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10
Q

Port loading

A

the amount of gas-air mixture passing through a burner that will create a stable flame

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11
Q

What is port loading burner express as?

A

BTUs / square inch of port area

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12
Q

How can the port loading be changed?

A

By altering the orifice size or gas pressure (manifold pressure)

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13
Q

Port loading (NG) bn 25,000 - 30,000 BTUs / square inch indicates what?

A

Stable flame

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14
Q

An atmospheric burner has a venturi that sucks primary air into where?

A

The burner / mixes air and gas before ignition

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15
Q

How do Mechanical burners get their supply requirements for air combustion?

A

They use a fan or blower

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16
Q

How are Mechanical burners categorized?

A

by:
1) location of the fan / blower in relation to the combustion chamber
2) Air pressure being delivered via burner / where the gas + air are mixed in the burner

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17
Q

What are the different kinds of Mechanical burners?

A

1) Forced Draft Burner
2) Induced Draft Burner
3) Balanced draft burner
4) Fan - assisted burner

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18
Q

What is a forced draft burner?

A

Combustion air is supplied by a fan or blower at sufficient pressure that overcomes resistance of the burner / appliance

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19
Q

How does a forced air burner work?

A

Supplies air to burner / forces products of combustion through the appliance

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20
Q

Where is the fan or blower located?

A

Upstream of the combustion zone

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21
Q

How does a induced draft burner operate?

A

Uses mechanical draft produced by a fan located downstream / chimney side of combustion zone

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22
Q

How is an Induced draft fan designed?

A

to pull in required air supply for combustion / vent products of combustion w/ positive vent pressure

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23
Q

How is the Balanced Draft burner different?

A

It’s a combination of forced / induced draft

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24
Q

Where are Balanced Draft burners mostly seen?

A

Larger boilers w/ multiple passes where the flue gases have to travel long distances

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25
Q

What is a Fan assisted burner?

A

Is a burner in which the combustion air is supplied by a mechanical device (fan / blower) at sufficient pressure to overcome the resistance of the burner only.

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26
Q

Where is the fan located?

A

upstream: fan assisted conversion burner
downstream: Fan assisted combustion system

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27
Q

Fan assisted systems give more precise control over what?

A

the air entering the combustion chamber

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28
Q

Mechanical combustion products are vented how?

A

Naturally w/ a nonpositive vent stack pressure

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29
Q

What is a pre-mix burner?

A

Mix the required amounts of air / gas before ignition

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30
Q

What are 3 types of pre-mix burners?
(MAG)

A

1) Inspirator or Gas Jet mixer
2) Aspirating Mixer
3) Mechanical Mixer

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31
Q

Inspirator burner uses what type of gas?

A

High pressure gas of 10 psi or more

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32
Q

Inspirators can entrain / pre mix up to what % of required combustion air?

A

100%

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33
Q

How does an Aspirating mixer work?

A

Uses pressurized air, issued at high velocity via venturi to entrain / mix gas

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34
Q

Aspirating mixer are common where?

A

on residential / commercial condensing boilers dt their excellent turndown

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35
Q

What does an Aspirating mixer use to mix gas?

A

Pressurized air at high velocity via a venturi

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36
Q

How is a Mechanical mixer straight forward?

A

uses a fan or blower to mix / supply air and gas to burner

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37
Q

How do burners create a stable flame?

A

by balancing the different combustion properties of gas - air mixture

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38
Q

What happens when combustion limits are exceeded?

A

The combustion process won’t generate enough heat and flame will go out

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39
Q

What are the 4 combustion properties that effect the burner flame?
(LIMM)

A

1) Limits of flammability
2) Max flame speed
3) Ignition temp
4) Max flame temp

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40
Q

What are limits of flammability?

A

the upper and lower ranges of gas that support combustion

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41
Q

What is max flame speed?

A

The velocity the flame front moves towards the air-gas mixture

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42
Q

What is NG burn ratio?

A

4-15% fuel

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43
Q

A stable flame will has a what?

A

A balanced air-gas flow velocity / flame speed (that keeps the flame front close to burner spot)

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44
Q

What is ignition temp?

A

Is the temp at which an air-gas mixture will initiate / support combustion

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45
Q

What is flame temperature?

A

Max flame temp can only be reached at perfect combustion

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46
Q

True or False: Each fuel gas has its own max flame temp.

A

True

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47
Q

What is NG ignition temp?

A

700C - 1300F

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48
Q

What is the ignition temp of Propane?

A

490C - 920F

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49
Q

What is the ignition temp of Butane?

A

1980C - 3600F

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50
Q

What is a flame retention device?

A

When gas-air mixtures flow into sheltered areas / burns –> generating enough heat to ignite gas/air mixture leaving the burner head

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51
Q

What is a flame stabilizing device?

A

Provides shelter for the air-gas mixture to essentially ignite

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52
Q

What is the basics of an atmospheric burner?

A

a device that requires no fans or electrical supply
burns gas simply / efficiently

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53
Q

What are the 2 types of atmospheric burners?

A

1) Luminous
2) Bunsen burner

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54
Q

What does the luminous flame depend on for combustion?

A

the air around the flame (secondary air)
(it does not premix gas-mix mixture)

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55
Q

Why does the luminous flame have a small blue flame / large yellow flame?

A

Blue flame: hydrogen burns fast
Yellow flame: Carbon burns hot

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56
Q

Why does the Bunsen flame more efficient?

A

It premixes air w/ gas prior to ignition

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57
Q

True or False: a stable atmospheric Bunsen burner flame has several colour zones

A

True
each zone marks a stage in burning of the gas

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58
Q

What is the inner cone of a Bunsen flame?

A

Here gas is burned to form products (aldehydes, alcohols, CO + H)
Is the blue flame
Unburned gas mixture forms the shape of flame

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59
Q

What is the Outer cone

A

Here the secondary air around the flame diffuses into the flame takes part in burning
Inner cone products are completely burned here

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60
Q

Where does the highest flame temp occur?

A

Just above the outer cone tip

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61
Q

What is the Outer mantle?

A
  • it’s colourless, surrounds outer cone
  • contains no unburned gases
  • Glows dt combustion products high temps
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62
Q

What are the 3 types of Bunsen flames?
(RON)

A

1) Reducing flame
2) Oxidizing flame
3) Neutral flame

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63
Q

What colour of flame will a Bunsen flame have if it’s stable?

A

Blue

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64
Q

What is a reducing flame?

A

Is a flame w/ low oxygen

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65
Q

What colour of flame will a reducing flame have?

A

Yellow dt the presence of unburned carbon (or hydrocarbons)

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66
Q

What’s the second name for a reducing flame?

A

Carburizing flame

67
Q

Why is it called a Carburizing flame?

A

When being brazed or welded carbon is introduced into molten metal…

68
Q

What is an oxidizing flame?

A

flame produced w/ an excessive amount of oxygen

69
Q

What happens when you increase oxygen in an oxidizing flame?

A

flame shortens
colour darkens
hisses / roar

70
Q

Is the oxidizing flame good or bad for welding / soldering?

A

No, it oxidizes the metal’s surface

71
Q

What is the neutral flame?

A

The amount of oxygen is enough for burning
Oxidation / reduction does not occur

72
Q

What colour of flame is the neutral flame?

A

clear blue due to a good balance of oxygen

73
Q

What happens when a cold surface touches the inner cone of a bunsen burner?

A

temp decreases / causes incomplete combustion

74
Q

What is an indicator of flame impingement?

A

Soot forming on the colder surface

75
Q

Can impingement cause incomplete combustion in the occur in the outer cone?

A

No, this flame is too hot / maintains the temp for combustion

76
Q

Is flow velocity the same at all points across a burner port?

A

No

77
Q

What is a venturi?

A

Is a short tube w/ a constricted, throat - like passage

78
Q

What does the narrowing passage of a venturi do?

A

Increases the velocity / creates a negative pressure in relation to the air surrounding the burner

79
Q

What does a negative pressure do?

A

Sucks atmospheric air in

80
Q

What is Bernoulli’s Theorem?

A

When velocity increases, the pressure decreases
When velocity decreases, the pressure increases

81
Q

What is an air shutter?

A

its used to adjust the size of air openings to control primary air flow

82
Q

What are the primary air control devices? (WBRS)

A
  • Wing
  • Butterfly
  • Rotating or sliding disc
  • Spoiler screw
83
Q

Is the orifice part of the burner?

A

No

84
Q

Gas pressure and orifice size controls what?

A

The volume / velocity of the gas being injected in the burner.

85
Q

What happens if you adjust the manifold (gas supply) pressure?

A

Change velocity of gas stream / venturi affect = changes primary air amount being drawn in

86
Q

What is a mixing tube?

A

Portion of the tube that mixes gas and air together

87
Q

What is a burner head?

A

Where gas/ air mixture enters the burner
Area is greatest - velocity is lowest and pressure is at its highest point

88
Q

Is a burner port an orifice?

A

Yes

89
Q

What does a burner port do?

A

1) discharges gas/ air mixture
2) distributes flames
3) spreads flanes
(More ports = more flames = more secondary air)

90
Q

What characteristics should a properly functioning burner have?

A
  • uniform heat
  • complete combustion
  • stable flames
  • ready ignition
  • quiet operation
91
Q

What does a small hard blue flame off of burner port indicate?

A

Too much primary air
Air shutter should be closed

92
Q

What does a soft, blurred or yellow tipped flame off the burner port indicate?

A

Lack of primary air
Air shutter should be opened

93
Q

What are 2 main categories of atmospheric burners?
(Main pilot in the atmosphere)

A

Main burner
Pilot burner

94
Q

What are 2 common types of atmospheric main burners?
(Main single multiport)

A

Single port
Multiport

95
Q

What in a Single port burner?

A

Has an inshot burner that fires HORIZONTALLY into heat exchanger

96
Q

What is an upshot burner?

A

Burns vertically
Common in domestic storage type water heaters

97
Q

What is the most common atmospheric burner used in appliances?

A

Multiport burners

98
Q

What is a burner bed?

A

When a number of multiport burners are used together

99
Q

What is a pilot burner?

A

A small flame used to ignite the main burner

100
Q

What are 2 types of pilot burners?
(A-NON)

A

Aerated pilots
Non-aerated pilots

101
Q

What do aerated pilots do?

A

They premix air and gas
Have a sharp blue flame
primary air is drawn through a tube or air duct

102
Q

Do aerated pilots have a stable flame?

A

yes and they produce higher flame temperatures

103
Q

What is the common problem with Aerated pilots?

A

clogging of the primary air openings due to dust and lint

104
Q

What are non-aerated pilots?

A

Have a short flame w/ little yellow colouring
Does not have dust / lint problems

105
Q

What are non-aerated pilots affected by?

A

drafts / main burner variations

106
Q

What are the most common problems w/ atmospheric burners?

A
  • flashback
  • Extinction pop
  • Flame lift off
  • Floating flames
  • Waving flames
  • Flame roll out
  • Yellow tipping
  • Fluctuating flames
  • Gas odour
107
Q

What happens in flashback?

A

Gas/ air mixture ignites inside the burner to burn near the orifice

108
Q

What kind of noise does flashback make?

A

roaring noise like a torch

109
Q

Flashback creates incomplete combustion which produces what?

A

Carbon monoxide / aldehydes

110
Q

Does flashback produce soot?

A

Yes due to incomplete combustion

111
Q

What causes flashback?

A

very lean gas/air mixture

112
Q

What eliminates Flashback?

A

reduce the primary air to the burner
(without produces yellow-tipped flames)

113
Q

If the burner is underfired (in flashback) what should happen?

A

Check input rate / adjust in to correct input value (orifice size / manifold pressure)

114
Q

What is extinction pop?

A

When flashback occurs when the burner is shut off

115
Q

What noise does an extinction pop make?

A

Bang

116
Q

When does extinction pop occur?

A

When the gas supply is turned off

117
Q

Is extinction pop dangerous?

A

No and will not damage appliance
Can blow out pilot light tho

118
Q

What are some remedies for extinction pop?

A

Reduce primary air supply to the burner

119
Q

Where is extinction pop a common problem?

A

on long atmospheric burners

120
Q

What is Flame liftoff?

A

It’s when part of the flame lifts or dances on the burner port

121
Q

What causes flame liftoff?

A

when flow velocity of the gas/air mixture from a burner port is greater than the flame burning speed
aka high gas pressure

122
Q

What kind of noise does a lifting flame create?

A

Roaring

123
Q

What is a concern of flame liftoff?

A

incomplete combustion may escape flames

124
Q

What are some remedies for lifting flames?

A

Reduce primary air
Also check, input is correct, orifice size / manifold pressure may need to be reduced first
(do not cause yellow tipping)

125
Q

What is yellow flame due to?

A

Lack of primary air

126
Q

What are Floating flames?

A

Are flames that do not have well-defined cones / appear to be reaching for air / roll around in the combustion chamber
flames are lazy looking

127
Q

What kind of odour is present w/ floating flames?

A

a strong aldehyde odor

128
Q

What do floating flames indicate?

A

incomplete combustion

129
Q

Are floating flames dangerous?

A

Yes

130
Q

What are some remedies for Floating flames?

A

appliance is overfired
2) Flue outlet too small
1) LACK OF SECONDARY AIR

131
Q

What is the cause of Floating flame?

A

Poor venting
check for blockages at the flue collar

132
Q

What is Waving flame?

A

is a result of drafts across burners = waving / unstable flame

133
Q

What can cause waving flame?

A

a cracked heat exchanger

134
Q

What are some remedies for waving flame?

A

eliminate external drafts across the floor
protect pilot with a suitable shield

135
Q

What occurs in Flame rollout?

A

When flames rollout of the front of the combustion chamber when the burners are ignited

136
Q

What can happen with Flame rollout?

A

fire hazard created, scorch appliance, burn wires or damage controls (can lead to flashblack)

137
Q

What are some remedies for flame rollout?

A

Increase secondary air?
Check for blockages

138
Q

What causes Flame rollout?

A

lack of combustion air dt over-firing of burners, poor draft or blockages in flue passage.

139
Q

What is Yellow tipping?

A

when there is not enough primary air

140
Q

What does yellow tipped flames indicate?

A

Incomplete combustion

141
Q

Does yellow flames produce soot?

A

Yes

142
Q

If there is a 1/32 build of of soot, this decreases efficiency losses by what?

A

16%

143
Q

What do red or orange streak indicate?

A

dirt or dust in the primary air supply

144
Q

What are remedies for yellow tipping?

A

Slowly open primary air shutter
Check the orifice - clean, realign or replace it if necessary.

145
Q

What are Fluctuating Flames?

A

flames fluctuate over a period of time w/o adjust the burner.

146
Q

Are fluctuating flames problematic?

A

No

147
Q

What are some remedies for fluctuating flames?
(The farting hunter)

A

Faulty oversized hunting regulator or undersized gas piping.

148
Q

What causes Fluctuating flames?

A

Unsteady gas pressures

149
Q

True or false: normal burner operation has a negative pressure (vacuum) inside the primary air opening that draws air in.

A

True

150
Q

How do you change input to a burner?

A

Adjust the manifold pressure or change area of the orifice

151
Q

What is the most common type of a main burner orifice?

A

Fixed (plug)

152
Q

Which gas range cap orifice has a higher heat value, cap is threaded clockwise = fixed flow through the needle hole?

A

Propane operation

153
Q

Which gas range cap orifice has a lower heat value, greater flow rate required – orifice cap is unthreaded counter clock wise, away from needle?

A

Natural Gas

154
Q

How is vol of gas (flow rate) expressed?

A

ft3 / hr - input = BTU / h
m3 / hr - input = kW

155
Q

How is the K factor determined?

A

angle of approach to the orifice
K = 0.9

156
Q

True or False: Heavier gas will flow less easily through an orifice.

A

True

157
Q

What are the specific gravities of propane, NG and butane?

A

NG = 0.6
Propane = 1.5
Butane = 2.0

158
Q

What does DMS mean?

A

Drill manufactured size

159
Q

True or False: Always choose the smaller orifice so that the appliance is not overfired.

A

True

160
Q

What is combustion air made of?

A

Primary air - 1/3 - mixed w/ gas
Secondary - 2/3 - Air around flame

161
Q

Where is excess air?

A

on the outlet side =
5ft3 / 1000BTU

162
Q

Draft control

A

is Dilution air
15ft3 / 1000BTU

163
Q

What is combustion air rated as?

A

10ft3/ 1000 BTUs
Requires 80% N2 / 20% O2

Plumbing Level 3 (26 decks)

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