TEXAS DEPARTMENT OF INSURANCE TFM10 NFPA 24 EXAM
2026-2027 - SPRINKLER UNDERGROUND PRACTICE
QUESTIONS, ANSWERS & TECHNICAL REVIEW
100 QUESTIONS
TABLE OF CONTENTS
# TOPIC
1 Analyze and apply NFPA 24 requirements for underground private fire service mains including sizing,
materials, and burial depth
2 Evaluate hydraulic calculations for underground piping, including friction loss, elevation, and available
water supply curves
3 Interpret code provisions for valves, hydrants, backflow prevention, thrust blocks, and testing/inspection
procedures
4 Diagnose compliance issues and prescribe corrective actions for underground sprinkler system
installations under TDI/Texas insurance standards
5 TEXAS DEPARTMENT OF INSURANCE TFM10 NFPA 24 EXAM 2026
6 2027
7 SPRINKLER UNDERGROUND PRACTICE QUESTIONS
8 ANSWERS & TECHNICAL REVIEW
9 Foundations of Texas Department of Insurance TFM10 - NFPA 24 Sprinkler Underground Practice
10 Applied Texas Department of Insurance TFM10 - NFPA 24 Sprinkler Underground Practice
11 Advanced Texas Department of Insurance TFM10 - NFPA 24 Sprinkler Underground Practice
12 Texas Department of Insurance TFM10 - NFPA 24 Sprinkler Underground Practice Review
ABSTRACT
Page 1
,This study document brings together 100 carefully worded exam questions drawn from TEXAS
DEPARTMENT OF INSURANCE TFM10 NFPA 24 EXAM 2026-2027 - SPRINKLER
UNDERGROUND PRACTICE QUESTIONS, ANSWERS & TECHNICAL REVIEW, with the
strongest emphasis placed on Analyze and apply NFPA 24 requirements for underground private
fire service mains including sizing, materials, and burial depth, Evaluate hydraulic calculations for
underground piping, including friction loss, elevation, and available water supply curves, Interpret
code provisions for valves, hydrants, backflow prevention, thrust blocks and and testing/inspection
procedures. Every item follows the wording style and level of reasoning you meet in the real paper,
and each one is paired with a clear rationale so the correct choice is never a guess. Work through
the set at your own pace, mark the questions that slow you down, then come back to them until the
reasoning feels automatic. Learners who revise this way walk into the exam room recognising the
pattern behind the questions instead of meeting them for the first time. Keep going - steady, honest
practice is what turns a difficult paper into a comfortable pass.
Q1 ANALYZE AND APPLY NFPA 24 REQUIREMENTS FOR UNDERGROUND PRIVATE FIRE
SERVICE MAINS INCLUDING SIZING, MATERIALS, AND BURIAL DEPTH
A private fire service main must supply a hydrant and a sprinkler riser. The
available static pressure is 65 psi at the city main, and the required residual
pressure at the most remote hydrant is 20 psi. If the total equivalent length of the
main from the city main to the hydrant is 800 ft and the flow is 1,500 gpm, what is
the maximum allowable friction loss per 100 ft (in psi) to meet the residual
pressure requirement? (Neglect elevation changes.)
A. 5.6 psi/100 ft CORRECT
B. 4.5 psi/100 ft
C. 6.0 psi/100 ft
D. 3.8 psi/100 ft
RATIONALE: Available pressure drop = 65 - 20 = 45 psi over 800 ft. Friction loss per 100 ft = (45
psi / 800 ft) × 100 = 5.625 psi/100 ft, approximately 5.6. Options B, C, and D misapply the
division or use incorrect pressure differences.
Page 2
,Q2 ANALYZE AND APPLY NFPA 24 REQUIREMENTS FOR UNDERGROUND PRIVATE FIRE
SERVICE MAINS INCLUDING SIZING, MATERIALS, AND BURIAL DEPTH
Which of the following pipe materials is NOT permitted by NFPA 24 for
underground private fire service mains unless specifically listed and approved for
fire service use?
A. Ductile iron pipe
B. PVC pipe listed for fire service
C. Asbestos-cement pipe CORRECT
D. Copper tube
RATIONALE: NFPA 24 prohibits asbestos-cement pipe due to health hazards and lack of listing
for fire service. Ductile iron, listed PVC, and copper are allowed when properly rated and installed
per the standard.
Q3 ANALYZE AND APPLY NFPA 24 REQUIREMENTS FOR UNDERGROUND PRIVATE FIRE
SERVICE MAINS INCLUDING SIZING, MATERIALS, AND BURIAL DEPTH
A backflow prevention assembly is installed on a private fire service main.
According to NFPA 24, which type of assembly is required when the public water
supply is subject to contamination and the fire system is directly connected?
A. Double check valve assembly
B. Reduced pressure zone (RPZ) backflow preventer CORRECT
C. Atmospheric vacuum breaker
D. Pressure vacuum breaker
RATIONALE: NFPA 24 requires an RPZ backflow preventer for direct connections where
contamination risk exists, as it provides the highest level of protection. Double check valves are
insufficient for health hazards, and vacuum breakers are not approved for this application.
Page 3
, Q4 ANALYZE AND APPLY NFPA 24 REQUIREMENTS FOR UNDERGROUND PRIVATE FIRE
SERVICE MAINS INCLUDING SIZING, MATERIALS, AND BURIAL DEPTH
During a hydrostatic test of a private fire service main, the test pressure must be
maintained for a specified duration. Which of the following correctly states the
NFPA 24 requirement for test pressure and duration?
A. 50 psi above working pressure for 1 hour
B. 200 psi or 50 psi above working pressure (whichever is greater) for 2 hours CORRECT
C. Working pressure for 4 hours
D. 150 psi for 30 minutes
RATIONALE: NFPA 24 requires a hydrostatic test at 200 psi or 50 psi above working pressure
(whichever is greater) for 2 hours, with no leakage. Other options do not meet the minimum
pressure or duration requirements.
Q5 ANALYZE AND APPLY NFPA 24 REQUIREMENTS FOR UNDERGROUND PRIVATE FIRE
SERVICE MAINS INCLUDING SIZING, MATERIALS, AND BURIAL DEPTH
A thrust block is required at a 90-degree elbow on a 12-inch ductile iron private fire
main with a working pressure of 150 psi. Using the NFPA 24 thrust block sizing
method, what is the primary factor that determines the required bearing area of the
thrust block?
A. The pipe diameter only
B. The soil bearing capacity and the resultant thrust force CORRECT
C. The length of the pipe run
D. The number of hydrants downstream
RATIONALE: Thrust block design depends on the thrust force (calculated from pressure and pipe
size) and the soil's bearing capacity. Pipe diameter alone is insufficient; soil conditions and force
magnitude dictate the block's bearing area.
Page 4
2026-2027 - SPRINKLER UNDERGROUND PRACTICE
QUESTIONS, ANSWERS & TECHNICAL REVIEW
100 QUESTIONS
TABLE OF CONTENTS
# TOPIC
1 Analyze and apply NFPA 24 requirements for underground private fire service mains including sizing,
materials, and burial depth
2 Evaluate hydraulic calculations for underground piping, including friction loss, elevation, and available
water supply curves
3 Interpret code provisions for valves, hydrants, backflow prevention, thrust blocks, and testing/inspection
procedures
4 Diagnose compliance issues and prescribe corrective actions for underground sprinkler system
installations under TDI/Texas insurance standards
5 TEXAS DEPARTMENT OF INSURANCE TFM10 NFPA 24 EXAM 2026
6 2027
7 SPRINKLER UNDERGROUND PRACTICE QUESTIONS
8 ANSWERS & TECHNICAL REVIEW
9 Foundations of Texas Department of Insurance TFM10 - NFPA 24 Sprinkler Underground Practice
10 Applied Texas Department of Insurance TFM10 - NFPA 24 Sprinkler Underground Practice
11 Advanced Texas Department of Insurance TFM10 - NFPA 24 Sprinkler Underground Practice
12 Texas Department of Insurance TFM10 - NFPA 24 Sprinkler Underground Practice Review
ABSTRACT
Page 1
,This study document brings together 100 carefully worded exam questions drawn from TEXAS
DEPARTMENT OF INSURANCE TFM10 NFPA 24 EXAM 2026-2027 - SPRINKLER
UNDERGROUND PRACTICE QUESTIONS, ANSWERS & TECHNICAL REVIEW, with the
strongest emphasis placed on Analyze and apply NFPA 24 requirements for underground private
fire service mains including sizing, materials, and burial depth, Evaluate hydraulic calculations for
underground piping, including friction loss, elevation, and available water supply curves, Interpret
code provisions for valves, hydrants, backflow prevention, thrust blocks and and testing/inspection
procedures. Every item follows the wording style and level of reasoning you meet in the real paper,
and each one is paired with a clear rationale so the correct choice is never a guess. Work through
the set at your own pace, mark the questions that slow you down, then come back to them until the
reasoning feels automatic. Learners who revise this way walk into the exam room recognising the
pattern behind the questions instead of meeting them for the first time. Keep going - steady, honest
practice is what turns a difficult paper into a comfortable pass.
Q1 ANALYZE AND APPLY NFPA 24 REQUIREMENTS FOR UNDERGROUND PRIVATE FIRE
SERVICE MAINS INCLUDING SIZING, MATERIALS, AND BURIAL DEPTH
A private fire service main must supply a hydrant and a sprinkler riser. The
available static pressure is 65 psi at the city main, and the required residual
pressure at the most remote hydrant is 20 psi. If the total equivalent length of the
main from the city main to the hydrant is 800 ft and the flow is 1,500 gpm, what is
the maximum allowable friction loss per 100 ft (in psi) to meet the residual
pressure requirement? (Neglect elevation changes.)
A. 5.6 psi/100 ft CORRECT
B. 4.5 psi/100 ft
C. 6.0 psi/100 ft
D. 3.8 psi/100 ft
RATIONALE: Available pressure drop = 65 - 20 = 45 psi over 800 ft. Friction loss per 100 ft = (45
psi / 800 ft) × 100 = 5.625 psi/100 ft, approximately 5.6. Options B, C, and D misapply the
division or use incorrect pressure differences.
Page 2
,Q2 ANALYZE AND APPLY NFPA 24 REQUIREMENTS FOR UNDERGROUND PRIVATE FIRE
SERVICE MAINS INCLUDING SIZING, MATERIALS, AND BURIAL DEPTH
Which of the following pipe materials is NOT permitted by NFPA 24 for
underground private fire service mains unless specifically listed and approved for
fire service use?
A. Ductile iron pipe
B. PVC pipe listed for fire service
C. Asbestos-cement pipe CORRECT
D. Copper tube
RATIONALE: NFPA 24 prohibits asbestos-cement pipe due to health hazards and lack of listing
for fire service. Ductile iron, listed PVC, and copper are allowed when properly rated and installed
per the standard.
Q3 ANALYZE AND APPLY NFPA 24 REQUIREMENTS FOR UNDERGROUND PRIVATE FIRE
SERVICE MAINS INCLUDING SIZING, MATERIALS, AND BURIAL DEPTH
A backflow prevention assembly is installed on a private fire service main.
According to NFPA 24, which type of assembly is required when the public water
supply is subject to contamination and the fire system is directly connected?
A. Double check valve assembly
B. Reduced pressure zone (RPZ) backflow preventer CORRECT
C. Atmospheric vacuum breaker
D. Pressure vacuum breaker
RATIONALE: NFPA 24 requires an RPZ backflow preventer for direct connections where
contamination risk exists, as it provides the highest level of protection. Double check valves are
insufficient for health hazards, and vacuum breakers are not approved for this application.
Page 3
, Q4 ANALYZE AND APPLY NFPA 24 REQUIREMENTS FOR UNDERGROUND PRIVATE FIRE
SERVICE MAINS INCLUDING SIZING, MATERIALS, AND BURIAL DEPTH
During a hydrostatic test of a private fire service main, the test pressure must be
maintained for a specified duration. Which of the following correctly states the
NFPA 24 requirement for test pressure and duration?
A. 50 psi above working pressure for 1 hour
B. 200 psi or 50 psi above working pressure (whichever is greater) for 2 hours CORRECT
C. Working pressure for 4 hours
D. 150 psi for 30 minutes
RATIONALE: NFPA 24 requires a hydrostatic test at 200 psi or 50 psi above working pressure
(whichever is greater) for 2 hours, with no leakage. Other options do not meet the minimum
pressure or duration requirements.
Q5 ANALYZE AND APPLY NFPA 24 REQUIREMENTS FOR UNDERGROUND PRIVATE FIRE
SERVICE MAINS INCLUDING SIZING, MATERIALS, AND BURIAL DEPTH
A thrust block is required at a 90-degree elbow on a 12-inch ductile iron private fire
main with a working pressure of 150 psi. Using the NFPA 24 thrust block sizing
method, what is the primary factor that determines the required bearing area of the
thrust block?
A. The pipe diameter only
B. The soil bearing capacity and the resultant thrust force CORRECT
C. The length of the pipe run
D. The number of hydrants downstream
RATIONALE: Thrust block design depends on the thrust force (calculated from pressure and pipe
size) and the soil's bearing capacity. Pipe diameter alone is insufficient; soil conditions and force
magnitude dictate the block's bearing area.
Page 4
