DC Third Class Stationary Boilers (323)
1. What is a boiler? A boiler is a closed pressure vessel designed to heat water
or generate steam by the combustion of fuel or by electricity, for heating or
power purposes.
2. What is the primary function of a stationary boiler? The primary function
is to convert water into steam or hot water for heating, processing, or power
generation in a fixed location.
3. What are the two main types of boilers? The two main types are fire-tube
boilers and water-tube boilers.
4. What is a fire-tube boiler? A fire-tube boiler is one in which hot gases from
combustion pass through tubes surrounded by water.
5. What is a water-tube boiler? A water-tube boiler is one in which water
circulates through tubes that are surrounded by hot combustion gases.
6. What is boiler capacity? Boiler capacity is the amount of steam or hot water
a boiler can produce per hour, typically measured in pounds per hour or boiler
horsepower.
7. What is one boiler horsepower equal to? One boiler horsepower equals
33,475 BTU per hour or the evaporation of 34.5 pounds of water per hour at
212°F.
8. What is working pressure? Working pressure is the normal operating
pressure at which a boiler operates safely under regular conditions.
9. What is maximum allowable working pressure (MAWP)? MAWP is the
highest pressure at which a boiler is designed to operate safely, as stamped on
the nameplate.
,10. What is steam? Steam is water in its gaseous state, formed when water is
heated to its boiling point and vaporizes.
11. What is saturated steam? Saturated steam is steam at the temperature
corresponding to its pressure, containing no moisture or superheat.
12. What is superheated steam? Superheated steam is steam heated beyond its
saturation temperature at a given pressure.
13. What is wet steam? Wet steam is steam that contains water droplets in
suspension, occurring when steam quality is less than 100%.
14. What is latent heat? Latent heat is the heat energy required to change
water to steam without changing temperature.
15. What is sensible heat? Sensible heat is heat that causes a change in
temperature of a substance without changing its state.
16. What is a BTU? A BTU (British Thermal Unit) is the amount of heat
required to raise one pound of water one degree Fahrenheit.
17. What is the purpose of a steam drum? The steam drum separates steam
from water and provides storage space for steam and water.
18. What is the water level in a boiler? Water level is the height of water in
the boiler, typically maintained in the middle of the gauge glass.
19. Why is proper water level important? Proper water level prevents
overheating of heating surfaces and ensures adequate steam separation and
boiler safety.
20. What is blowdown? Blowdown is the process of removing water from the
boiler to control concentration of dissolved solids and sediment.
21. What is bottom blowdown? Bottom blowdown removes sediment and
sludge that settles at the bottom of the boiler.
22. What is surface blowdown? Surface blowdown removes suspended solids
and foam from the water surface in the steam drum.
23. What is carryover? Carryover is the entrainment of water droplets or
impurities with steam leaving the boiler.
24. What causes carryover? Carryover is caused by high water level, high
dissolved solids, improper chemical treatment, or sudden load changes.
25. What is priming? Priming is the violent surging of water in the boiler
causing slugs of water to be carried over with steam.
, 26. What is foaming? Foaming is the formation of stable bubbles on the water
surface due to dissolved solids or contamination.
27. What is scale? Scale is a hard deposit that forms on heating surfaces from
minerals in the boiler water.
28. Why is scale dangerous? Scale acts as an insulator, reducing heat transfer
and causing tube overheating and potential failure.
29. What is feedwater? Feedwater is the treated water supplied to the boiler to
replace water converted to steam or lost through blowdown.
30. What is makeup water? Makeup water is the fresh water added to the
system to replace water lost through steam use, leaks, or blowdown.
Section 2: Boiler Components (Questions 31-60)
31. What is a safety valve? A safety valve is a pressure-relief device that
automatically opens to prevent boiler pressure from exceeding the MAWP.
32. How many safety valves are required on a boiler? At least one safety
valve is required; two or more may be required depending on heating surface
area and regulations.
33. What is the purpose of a pressure gauge? A pressure gauge indicates the
steam or water pressure inside the boiler.
34. Where should a pressure gauge be located? The pressure gauge should be
located where it is easily visible to the operator.
35. What is a gauge glass? A gauge glass is a transparent tube that shows the
water level in the boiler.
36. How often should gauge glass be tested? The gauge glass should be tested
at the start of each shift by blowing down to ensure it is functioning properly.
37. What is a fusible plug? A fusible plug is a safety device with a metal core
that melts at a specific temperature to warn of low water conditions.
38. Where is a fusible plug located? It is located in the crown sheet or highest
heating surface area of fire-tube boilers.
39. What is a water column? A water column is a chamber connected to the
boiler that houses the gauge glass and water level controls.
40. What is the purpose of a steam stop valve? The steam stop valve isolates
the boiler from the steam line for maintenance or emergency shutdown.
1. What is a boiler? A boiler is a closed pressure vessel designed to heat water
or generate steam by the combustion of fuel or by electricity, for heating or
power purposes.
2. What is the primary function of a stationary boiler? The primary function
is to convert water into steam or hot water for heating, processing, or power
generation in a fixed location.
3. What are the two main types of boilers? The two main types are fire-tube
boilers and water-tube boilers.
4. What is a fire-tube boiler? A fire-tube boiler is one in which hot gases from
combustion pass through tubes surrounded by water.
5. What is a water-tube boiler? A water-tube boiler is one in which water
circulates through tubes that are surrounded by hot combustion gases.
6. What is boiler capacity? Boiler capacity is the amount of steam or hot water
a boiler can produce per hour, typically measured in pounds per hour or boiler
horsepower.
7. What is one boiler horsepower equal to? One boiler horsepower equals
33,475 BTU per hour or the evaporation of 34.5 pounds of water per hour at
212°F.
8. What is working pressure? Working pressure is the normal operating
pressure at which a boiler operates safely under regular conditions.
9. What is maximum allowable working pressure (MAWP)? MAWP is the
highest pressure at which a boiler is designed to operate safely, as stamped on
the nameplate.
,10. What is steam? Steam is water in its gaseous state, formed when water is
heated to its boiling point and vaporizes.
11. What is saturated steam? Saturated steam is steam at the temperature
corresponding to its pressure, containing no moisture or superheat.
12. What is superheated steam? Superheated steam is steam heated beyond its
saturation temperature at a given pressure.
13. What is wet steam? Wet steam is steam that contains water droplets in
suspension, occurring when steam quality is less than 100%.
14. What is latent heat? Latent heat is the heat energy required to change
water to steam without changing temperature.
15. What is sensible heat? Sensible heat is heat that causes a change in
temperature of a substance without changing its state.
16. What is a BTU? A BTU (British Thermal Unit) is the amount of heat
required to raise one pound of water one degree Fahrenheit.
17. What is the purpose of a steam drum? The steam drum separates steam
from water and provides storage space for steam and water.
18. What is the water level in a boiler? Water level is the height of water in
the boiler, typically maintained in the middle of the gauge glass.
19. Why is proper water level important? Proper water level prevents
overheating of heating surfaces and ensures adequate steam separation and
boiler safety.
20. What is blowdown? Blowdown is the process of removing water from the
boiler to control concentration of dissolved solids and sediment.
21. What is bottom blowdown? Bottom blowdown removes sediment and
sludge that settles at the bottom of the boiler.
22. What is surface blowdown? Surface blowdown removes suspended solids
and foam from the water surface in the steam drum.
23. What is carryover? Carryover is the entrainment of water droplets or
impurities with steam leaving the boiler.
24. What causes carryover? Carryover is caused by high water level, high
dissolved solids, improper chemical treatment, or sudden load changes.
25. What is priming? Priming is the violent surging of water in the boiler
causing slugs of water to be carried over with steam.
, 26. What is foaming? Foaming is the formation of stable bubbles on the water
surface due to dissolved solids or contamination.
27. What is scale? Scale is a hard deposit that forms on heating surfaces from
minerals in the boiler water.
28. Why is scale dangerous? Scale acts as an insulator, reducing heat transfer
and causing tube overheating and potential failure.
29. What is feedwater? Feedwater is the treated water supplied to the boiler to
replace water converted to steam or lost through blowdown.
30. What is makeup water? Makeup water is the fresh water added to the
system to replace water lost through steam use, leaks, or blowdown.
Section 2: Boiler Components (Questions 31-60)
31. What is a safety valve? A safety valve is a pressure-relief device that
automatically opens to prevent boiler pressure from exceeding the MAWP.
32. How many safety valves are required on a boiler? At least one safety
valve is required; two or more may be required depending on heating surface
area and regulations.
33. What is the purpose of a pressure gauge? A pressure gauge indicates the
steam or water pressure inside the boiler.
34. Where should a pressure gauge be located? The pressure gauge should be
located where it is easily visible to the operator.
35. What is a gauge glass? A gauge glass is a transparent tube that shows the
water level in the boiler.
36. How often should gauge glass be tested? The gauge glass should be tested
at the start of each shift by blowing down to ensure it is functioning properly.
37. What is a fusible plug? A fusible plug is a safety device with a metal core
that melts at a specific temperature to warn of low water conditions.
38. Where is a fusible plug located? It is located in the crown sheet or highest
heating surface area of fire-tube boilers.
39. What is a water column? A water column is a chamber connected to the
boiler that houses the gauge glass and water level controls.
40. What is the purpose of a steam stop valve? The steam stop valve isolates
the boiler from the steam line for maintenance or emergency shutdown.
