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Plumbing Level 3 > E5 - self test questions > Flashcards

E5 - self test questions Flashcards

1
Q

What term refers to the min input of fuel that is required to keep a burner from flaming out?

A

Low-fire

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2
Q

What term is used to help determine how low a boiler can modulate from max firing rate before it turns off?

A

Turndown ratio

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3
Q

What type of burner relies upon atmospheric pressure to supply all of its combustion air?

A

non-mechanical burner

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4
Q

What type of burner uses a fan located downstream of the combustion zone to pull in the air supply for combustion / vent the products of combustion w/ a positive vent pressure?

A

Induced draft burner

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5
Q

What type of burner uses a mechanical device to supply combustion air at the pressure necessary to only overcome the resistance of the burner?

A

Fan-assisted burner

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6
Q

What type of mechanical burner relies on the products of combustion to be vented naturally w/ a nonpositive vent stack pressure?

A

Fan-assisted burner

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7
Q

What type of pre-mix burner has become very common in residential condensing boilers?

A

Aspirating mixer

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8
Q

What are the limits of Flammability for NG?

A

4 - 15%

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9
Q

What is the approximate max flame temp for propane, Butane and NG?

A

1980C

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10
Q

What is the purpose of burner flame retention devices?

A

Reduce gas mixture velocity

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11
Q

True or False: A luminous flame burner does not premix gas / air before ignition

A

True

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12
Q

True or False: A bunsen burner produces a large glowing yellow flame

A

False

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13
Q

A bunsen burner premixes the air w/ the gas before it is ignited

A

True

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14
Q

Which type of Bunsen flame has a yellowish colour due to the presence of unburned carbon or hydrocarbons

A

Reducing flame

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15
Q

Which type Bunsen flame has a hissing shortened flame?

A

Oxidizing flame

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16
Q

True or False: The flow velocity is highest at the centerline of the burner port opening

A

True

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17
Q

What part of the burner increases the gas velocity / creates a negative pressure used to suck in the combustion air?

A

Venturi

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18
Q

True or False: The manifold pressure require for an atmospheric burner operating on propane gas is typically 2.5 x higher than that required for natural gas, in order to draw in the higher ratio of primary air required

A

True

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19
Q

One of the 2 pilot burner categories describes their ability to premix air. What does the other category describe?

A

Ignition Sequence

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20
Q

If flashback is occurring in an atmospheric burner, which of the following actions may be required?

A

Decrease the primary air and/or increase the gas pressure.

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21
Q

How can flame lift off be corrected?

A

Decrease the primary air

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22
Q

What usually causes a noisy, lifting, blowing pilot flame?

A

High gas pressure

23
Q

Which of the following conditions would cause a floating flame?

A

A blocked vent

24
Q

What could be the problem w/ a furnace if a flame is waving or rolling out when the air circulation fan comes on?

A

A cracked heat exchanger

25
Q

There are 2 methods of changing the input to the burner, one is by adjusting the manifold pressure what is the other?

A

Changing the size of the orifices

26
Q

The 3 common types of main burner orifices are?

A

1) Fixed
2) Adjustable
3) Cap

27
Q

Which type of orifice can commonly be found on dual fuel (propane / NG) appliances?

A

Cap or universal

28
Q

How is a residential range w/ universal orifices converted from propane to NG?

A

Turn the orifice cap counter - clockwise / change the regulator setting

29
Q

True or False: It is the diameter that is used to calculate the flow rate through an orifice not the area

A

False

30
Q

What is the smallest drill size?

A

3/32”

31
Q

Which factor does not affect the sizing of the burner orifice?

A

Position of the burner in relation to the pilot

32
Q

When using a rotary meter to clock a boiler the LED flow rate screen meter indicates 3.54m cubed / hour of NG. What is the appliance input?

A

36.64 kW

33
Q

1000 BTU/ft3
meter pressure = 7” WC
30 sec for test dial to make 1 revolution. What is the appliance input?

A

60,000BTU/h

34
Q

True or False: The propane gas orifice sizes are smaller then the required NG orifices for the same appliance.

A

True

35
Q

What are the 3 common pilot ignition systems?

A

1) Continuous
2) Intermittent
3) Interrupted

36
Q

Which of the pilot ignition system is the pilot flame typically also being used on a heat activated safety device such as a thermocouple?

A

Continuous pilot

37
Q

Which of the pilot ignition systems does the pilot flame remain lit throughout the main burner cycle / when the call for heat is satisfied the pilot / main burners are shut off?

A

Intermittent pilot

38
Q

Which of the pilot ignition systems is the pilot flame extinguished when the main burner has been ignited?

A

Interrupted pilot

39
Q

The point at which the 2 dissimilar metals are joined on a thermocouple is known as what?

A

Hot junction

40
Q

Thermocouples are used w/ which type of pilot?

A

Standing pilot

41
Q

What portion of the hot junction should be heated by the pilot flame?

A

First 0.375” - 0.5” thermocouple

42
Q

What does a thermocouple power when it is being heated?

A

Safety coil

43
Q

True or False: A thermopile contains approximately 10 - 30 thermocouples

A

True

44
Q

How are multiple thermocouples electrically connected w/ in a thermopile?

A

Series

45
Q

What setting should a multimeter be on measuring the flame sensing circuit?

A

uAmps DC

46
Q

Flame rods for spark ignition systems are typically made of what high temperature resistant alloy?

A

Kanthol

47
Q

What is the primary purpose of a thermocouple?

A

To prove that the pilot is lit

48
Q

What is the max time allowed in the event of pilot outage for the thermocouple to cool down / stop the flow of gas to the burner?

A

90 Seconds

49
Q

What type of current do thermocouples / thermopiles produce?

A

DC

50
Q

True or False: A thermocouple must be under load to perform an open circuit test.

A

False

51
Q

What reading should an open circuit test on a thermocouple produce?

A

30mV

52
Q

What does a closed - circuit test show?

A

Millivolt maintained under load

53
Q

A thermocouple should be replaced if it cannot produce a closed circuit reading of more than…

A

9 mV

54
Q

During a pilot-stat coil test at what mV reading should the coil drop out?

A

Between 5 - 2 mV

Plumbing Level 3 (26 decks)

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