DC 3RD CLASS TEST EXAM(ACTUAL EXAM)
WITH CORRECT ACTUAL QUESTIONS AND
CORRECTLY WELL DEFINED ANSWERS
LATEST ALREADY GRADED A+ 2026
What is pump slip?
The difference the pumps theoretical and actual pump
displacement
What is shear?
it is the exertion of equal forces in opposite direction in the
same plane
What compound is not a heat producer?
Nitrogen
How many BTUs does it take to raise 10LB of water from 40
to 41?
40-41=1
1 x 10= 10
10 BTUs
How is moisture removed from a refrigerant system?
Filter Drier
,Know your type of controls?
Discrete and Analog
How much excess air is required to burn coal?
50 %
What is a condenser?
The part of the refrigeration system that receives hot, high
pressure gas from the compressor and cools it until it returns
to a liquid state
What is an evaporator?
The part of a refrigeration system in which the liquid
refrigerant vaporizes and absorbs latent heat
Which by product fuel has the LOWES heating value?
Blast furnace gas
How much excess air is needed for the proper combustion
of coal, gas or oil?
10% to 30%
What type of flame detector senses inferred light?
Lead sulfide photocell
What is an accumulation test used for?
To test the relieving capacity of safety valves to insure they
are proper size
What is a hydrostatic test?
,Filling the boiler with 70 degrees F water and raising the
pressure to 1 1/2 times the MAWP to test for leaks and
weaknesses
What is the maximum toxicity level for a class B refrigerant?
400 ppm
A cadmium sulfide photocell senses what?
Visible Light
What is a foot valve?
a device that works as a check valve in both direction and
keeps pump primed
Which gas byproduct? Byproduct gas has the highest heat
value (BTU)
Butane
What percentage of pressure should a boiler have before
you test the lever of safety valve?
75% superheat valves are pressure
Name the wire that connects all component of a system to a
physical ground or water pipe?
Grounding electrode conductor
Where do you get sub-cooling reading?
Take liquid line pressure
Cross reference to temperature using a P/T Chart
Get liquid line temperature
, Subtract actual temperature from cross referenced
temperature
Result is Sub cooling
On the boilers that have both Quick opening and Screw type
blow down valves, the Quick opening valve must be
located?
closest to the boiler and followed by the screw-type valve
High pressure boilers equipped with Quick opening and
Screw type valves are blown down how?
By opening the Quick opening valve first and closing it Last.
ASME Code defines a slow opening valve as what?
One requiring at least 5 full 360 degree turns between full
open and close position.
A 300 Horsepower boiler operating at 100psi has an average
load of 75% with 80% condensate return and 5% blow
down. The treatment provides a chemical which costs $8.75
per gallon, and will treat 600 gallon. Find the amount of the
chemical needed for the day period, and the cost of the
chemical for a 30 days period?
Water In = Water Out
Makeup + Condensate Return = Evaporator + Blow Down
Average Evaporator Rate = 300 x 34.5 pph x .75% load = 7762,
50 pph
WITH CORRECT ACTUAL QUESTIONS AND
CORRECTLY WELL DEFINED ANSWERS
LATEST ALREADY GRADED A+ 2026
What is pump slip?
The difference the pumps theoretical and actual pump
displacement
What is shear?
it is the exertion of equal forces in opposite direction in the
same plane
What compound is not a heat producer?
Nitrogen
How many BTUs does it take to raise 10LB of water from 40
to 41?
40-41=1
1 x 10= 10
10 BTUs
How is moisture removed from a refrigerant system?
Filter Drier
,Know your type of controls?
Discrete and Analog
How much excess air is required to burn coal?
50 %
What is a condenser?
The part of the refrigeration system that receives hot, high
pressure gas from the compressor and cools it until it returns
to a liquid state
What is an evaporator?
The part of a refrigeration system in which the liquid
refrigerant vaporizes and absorbs latent heat
Which by product fuel has the LOWES heating value?
Blast furnace gas
How much excess air is needed for the proper combustion
of coal, gas or oil?
10% to 30%
What type of flame detector senses inferred light?
Lead sulfide photocell
What is an accumulation test used for?
To test the relieving capacity of safety valves to insure they
are proper size
What is a hydrostatic test?
,Filling the boiler with 70 degrees F water and raising the
pressure to 1 1/2 times the MAWP to test for leaks and
weaknesses
What is the maximum toxicity level for a class B refrigerant?
400 ppm
A cadmium sulfide photocell senses what?
Visible Light
What is a foot valve?
a device that works as a check valve in both direction and
keeps pump primed
Which gas byproduct? Byproduct gas has the highest heat
value (BTU)
Butane
What percentage of pressure should a boiler have before
you test the lever of safety valve?
75% superheat valves are pressure
Name the wire that connects all component of a system to a
physical ground or water pipe?
Grounding electrode conductor
Where do you get sub-cooling reading?
Take liquid line pressure
Cross reference to temperature using a P/T Chart
Get liquid line temperature
, Subtract actual temperature from cross referenced
temperature
Result is Sub cooling
On the boilers that have both Quick opening and Screw type
blow down valves, the Quick opening valve must be
located?
closest to the boiler and followed by the screw-type valve
High pressure boilers equipped with Quick opening and
Screw type valves are blown down how?
By opening the Quick opening valve first and closing it Last.
ASME Code defines a slow opening valve as what?
One requiring at least 5 full 360 degree turns between full
open and close position.
A 300 Horsepower boiler operating at 100psi has an average
load of 75% with 80% condensate return and 5% blow
down. The treatment provides a chemical which costs $8.75
per gallon, and will treat 600 gallon. Find the amount of the
chemical needed for the day period, and the cost of the
chemical for a 30 days period?
Water In = Water Out
Makeup + Condensate Return = Evaporator + Blow Down
Average Evaporator Rate = 300 x 34.5 pph x .75% load = 7762,
50 pph
