NJ Black Seal Exam Preparation Version 3
Newest With Complete Questions And Correct
Detailed Answers| Brand New Version!
1. As solids and alkalinity in boiler water increase.
• ANSWER: Waterside scaling is increased.
Rationale: High solids and alkalinity lead to calcium carbonate and other
scale deposits on heating surfaces.
2. What chemical would be used to control scale in a low pressure boiler?
• ANSWER: Phosphate
Rationale: Phosphates precipitate calcium as hydroxyapatite sludge, which
can be removed by blowdown.
3. What will excessive oxygen in the boiler water cause?
• ANSWER: Pitting of boiler metal
Rationale: Dissolved oxygen causes localized corrosion (pitting) on boiler
tubes and drums.
4. By N.J.A.C. 12:90 what is the minimum thickness allowed for atmospheric
blowdown tank?
• ANSWER: 5/16 inch
*Rationale: The NJ code specifies minimum 5/16″ wall thickness for
atmospheric blowdown tanks.*
5. In the state of NJ, when is it permissible to have only one bottom blow off
valve?
• ANSWER: When MAWP does not exceed 100 PSI
Rationale: N.J.A.C. 12:90 allows a single blowdown valve for boilers with
maximum allowable working pressure ≤100 psi.
6. N.J.A.C requires the sewer lines be protected from high temperatures and
pressure from boiler blow off lines by a:
, • ANSWER: Blowdown tank
Rationale: A blowdown tank cools and depressurizes blowdown water
before discharging to sewer.
7. What effect would frequent blowing down of a boiler have on a system?
• ANSWER: Blow down heat loss
Rationale: Each blowdown removes hot water, reducing thermal efficiency.
8. The maximum size of the bottom blowdown line and surface line?
• ANSWER: 2.5 inch
Rationale: NJ code limits blowdown piping to 2.5″ NPS maximum.
9. As the firing rate increases in a boiler equipped with a convection superheater,
the steam temperature:
• ANSWER: Increases
Rationale: Convection superheaters absorb more heat as flue gas velocity
and temperature rise.
10. Before a hydrostatic test is performed on a boiler, each safety valve should be:
• ANSWER: Held to its seat by means of a testing clamp
Rationale: Safety valves must be clamped or gagged to prevent opening
during hydrostatic test (above set pressure).
11. What boiler should never be subjected to an accumulation test?
• ANSWER: A boiler equipped with a superheater
Rationale: Superheaters can be damaged by lack of steam flow during
accumulation test.
12. What is the difference between the set-point pressure at which a safety valve
opens and the pressure at which this valve closes?
• ANSWER: Blowback (also called blowdown)
Rationale: Blowback (or blowdown) is the pressure difference between
opening and reseating.
13. According to NJ code, the minimum allowable diameter for a bottom
blowdown pipe is:
, • ANSWER: 1 inch
Rationale: N.J.A.C. 12:90 requires bottom blowdown piping minimum 1″
NPS.
14. A boiler operator discovers a cracked gauge glass. The first action should be to:
• ANSWER: Shut off the gauge glass valves and replace the glass
Rationale: Isolating the glass prevents steam/water release; repair or
replace immediately.
15. When a boiler is in service, the water level should be maintained:
• ANSWER: Between the middle and top of the gauge glass
Rationale: Normal operating level is slightly above the midpoint to avoid
low-water condition.
16. The purpose of a surface blowdown (continuous blowdown) is to:
• ANSWER: Remove dissolved solids from the water surface
Rationale: Surface blowdown removes scum, oil, and dissolved solids that
concentrate near the water line.
17. A low water fuel cut-off device must be tested:
• ANSWER: Daily when boiler is under pressure
Rationale: NJ code requires daily low-water cutoff test (blowdown test)
while boiler is operating.
18. The maximum allowable working pressure (MAWP) of a heating boiler in NJ
is typically:
• ANSWER: 160 PSI for steam, 160 PSI for water (or 250°F)
Rationale: Low-pressure heating boilers ≤15 psi steam, ≤160 psi water. For
power boilers, higher. Question ambiguous – but common exam answer: 15
psi steam, 160 psi hot water.
19. Which valve is installed between the boiler and the main stop valve?
• ANSWER: A non-return valve (check valve)
Rationale: A non-return valve prevents backflow from the header into the
boiler.
20. A boiler hydrostatic test pressure should be:
Newest With Complete Questions And Correct
Detailed Answers| Brand New Version!
1. As solids and alkalinity in boiler water increase.
• ANSWER: Waterside scaling is increased.
Rationale: High solids and alkalinity lead to calcium carbonate and other
scale deposits on heating surfaces.
2. What chemical would be used to control scale in a low pressure boiler?
• ANSWER: Phosphate
Rationale: Phosphates precipitate calcium as hydroxyapatite sludge, which
can be removed by blowdown.
3. What will excessive oxygen in the boiler water cause?
• ANSWER: Pitting of boiler metal
Rationale: Dissolved oxygen causes localized corrosion (pitting) on boiler
tubes and drums.
4. By N.J.A.C. 12:90 what is the minimum thickness allowed for atmospheric
blowdown tank?
• ANSWER: 5/16 inch
*Rationale: The NJ code specifies minimum 5/16″ wall thickness for
atmospheric blowdown tanks.*
5. In the state of NJ, when is it permissible to have only one bottom blow off
valve?
• ANSWER: When MAWP does not exceed 100 PSI
Rationale: N.J.A.C. 12:90 allows a single blowdown valve for boilers with
maximum allowable working pressure ≤100 psi.
6. N.J.A.C requires the sewer lines be protected from high temperatures and
pressure from boiler blow off lines by a:
, • ANSWER: Blowdown tank
Rationale: A blowdown tank cools and depressurizes blowdown water
before discharging to sewer.
7. What effect would frequent blowing down of a boiler have on a system?
• ANSWER: Blow down heat loss
Rationale: Each blowdown removes hot water, reducing thermal efficiency.
8. The maximum size of the bottom blowdown line and surface line?
• ANSWER: 2.5 inch
Rationale: NJ code limits blowdown piping to 2.5″ NPS maximum.
9. As the firing rate increases in a boiler equipped with a convection superheater,
the steam temperature:
• ANSWER: Increases
Rationale: Convection superheaters absorb more heat as flue gas velocity
and temperature rise.
10. Before a hydrostatic test is performed on a boiler, each safety valve should be:
• ANSWER: Held to its seat by means of a testing clamp
Rationale: Safety valves must be clamped or gagged to prevent opening
during hydrostatic test (above set pressure).
11. What boiler should never be subjected to an accumulation test?
• ANSWER: A boiler equipped with a superheater
Rationale: Superheaters can be damaged by lack of steam flow during
accumulation test.
12. What is the difference between the set-point pressure at which a safety valve
opens and the pressure at which this valve closes?
• ANSWER: Blowback (also called blowdown)
Rationale: Blowback (or blowdown) is the pressure difference between
opening and reseating.
13. According to NJ code, the minimum allowable diameter for a bottom
blowdown pipe is:
, • ANSWER: 1 inch
Rationale: N.J.A.C. 12:90 requires bottom blowdown piping minimum 1″
NPS.
14. A boiler operator discovers a cracked gauge glass. The first action should be to:
• ANSWER: Shut off the gauge glass valves and replace the glass
Rationale: Isolating the glass prevents steam/water release; repair or
replace immediately.
15. When a boiler is in service, the water level should be maintained:
• ANSWER: Between the middle and top of the gauge glass
Rationale: Normal operating level is slightly above the midpoint to avoid
low-water condition.
16. The purpose of a surface blowdown (continuous blowdown) is to:
• ANSWER: Remove dissolved solids from the water surface
Rationale: Surface blowdown removes scum, oil, and dissolved solids that
concentrate near the water line.
17. A low water fuel cut-off device must be tested:
• ANSWER: Daily when boiler is under pressure
Rationale: NJ code requires daily low-water cutoff test (blowdown test)
while boiler is operating.
18. The maximum allowable working pressure (MAWP) of a heating boiler in NJ
is typically:
• ANSWER: 160 PSI for steam, 160 PSI for water (or 250°F)
Rationale: Low-pressure heating boilers ≤15 psi steam, ≤160 psi water. For
power boilers, higher. Question ambiguous – but common exam answer: 15
psi steam, 160 psi hot water.
19. Which valve is installed between the boiler and the main stop valve?
• ANSWER: A non-return valve (check valve)
Rationale: A non-return valve prevents backflow from the header into the
boiler.
20. A boiler hydrostatic test pressure should be:
