NFPA 24 TEST (TFM10) CORRECTLY ANSWERED
QUESTIONS!!
Introduction
This simulated examination replicates the scope, depth, and cognitive level of the NFPA
24 (Standard for the Installation of Private Fire Service Mains and Their Appurtenances)
TFM10 certification assessment. The test evaluates competency in underground pipe
installation, fire-hydrant placement, valve and appurtenance requirements, material
specifications, trenching and backfill practices, and acceptance testing/flushing
protocols. All items align with the 2022 edition of NFPA 24 and are designed to support
mastery-level performance on the actual certification exam.
General Instructions
• Read each scenario carefully; select the ONE best answer.
• Each correct response is supported by a concise code citation and rationale.
• The exam length matches the live TFM10 format: 60 questions (all scored).
• Marking criteria: +1 for each correct answer; 0 for incorrect.
• Passing score and weighting follow current NFPA/ProBoard policies (consult
your exam bulletin).
Exam Items
Question 1
A 200-mm (8 in.) private fire service main is being installed under a reinforced concrete
roadway. The trench bottom is undisturbed clay that is level and smooth. The pipe is
cement-lined ductile-iron. Which statement about bedding is correct?
A. A 100 mm sand bedding is required under the full length of pipe
B. Bedding is not required because the clay is non-settling
C. A 150 mm layer of crushed stone is mandatory for corrosion protection
D. Bedding must be placed to provide uniform support along the barrel excluding the
bell
Answer: D. Bedding must be placed to provide uniform support along the barrel
excluding the bell
Solution: NFPA 24 (2022) §6.2.2.1 requires uniform bedding support; bells are left
pg. 1
,unsupported to prevent point loading. Bedding material is required regardless of native
soil (A, B incorrect) and crushed stone alone (C) is not mandated.
Question 2
During installation, a 150 mm PVC fire main is exposed to ambient temperature of 4 °C.
After pressure testing, the pipeline must be:
A. Buried immediately to prevent freezing
B. Kept pressurized until backfill to prevent uplift
C. Drained completely before nightfall
D. Insulated with heat trace prior to test water introduction
Answer: B. Kept pressurized until backfill to prevent uplift
Solution: §7.2.5.1 allows shallow bury in cold climates if pipe remains pressurized to
resist flotation and ice expansion. Draining (C) wastes test water and time; insulation
(D) is not required by code.
Question 3
A contractor proposes locating a post-indicator valve (PIV) 2.1 m (7 ft) above the
finished grade for ease of operation. What is required by NFPA 24?
A. Acceptable if handle is accessible from a permanent platform
B. Acceptable if the valve is frost-proof
C. Not acceptable; maximum height is 1.2 m (4 ft)
D. Acceptable if an extension stem is installed to bring handle to 1.1 m
Answer: D. Acceptable if an extension stem is installed to bring handle to 1.1 m
Solution: §6.3.5.3 limits operating nut height to 0.3–1.1 m (12–42 in.). Extension stems
(D) are the compliant solution; platforms (A) are not addressed as substitutes.
Question 4
Which depth of cover is the minimum acceptable for a 200 mm ductile-iron fire service
main under an unimproved parking lot subject to light-truck traffic?
A. 0.45 m (18 in.)
B. 0.6 m (24 in.)
C. 0.75 m (30 in.)
D. 0.9 m (36 in.)
Answer: C. 0.75 m (30 in.)
Solution: Table 6.4.1.1 requires 30 in. minimum cover for pipe sizes ≥6 in. under light
vehicular loads. Lesser depths (A, B) are only permitted under sidewalks or with
concrete caps.
pg. 2
, Question 5
After final installation, a 300 m section of 150 mm cement-lined ductile-iron main is
hydrostatically tested. What is the minimum test pressure and duration?
A. 1.5 × working pressure for 30 min
B. 13.8 bar (200 psi) for 2 h
C. 13.8 bar (200 psi) or 1.5 × working pressure, whichever is greater, for 2 h
D. 20.7 bar (300 psi) for 1 h
Answer: C. 13.8 bar (200 psi) or 1.5 × working pressure, whichever is greater, for 2
h
Solution: §10.10.2.2.1 specifies the greater of 200 psi or 1.5 × working pressure for 2 h.
Option A duration is too short; 300 psi (D) is not required.
Question 6
A fire hydrant is installed on an 8 in. main. The hydrant has one 4½ in. pumper outlet
and two 2½ in. hose outlets. What is the minimum nominal diameter of the buried
hydrant lead?
A. 4 in.
B. 6 in.
C. 8 in.
D. 3 in.
Answer: B. 6 in.
Solution: §6.5.2.1 requires hydrant leads to be at least 6 in. nominal diameter to ensure
adequate flow regardless of main size.
Question 7
During flushing of a new 250 mm main, the contractor obtains a flow of 3.2 m³/min
(850 gpm) with a pitot pressure of 1.0 bar (14.5 psi) at a 64 mm (2½ in.) outlet. Which
statement is correct?
A. Flow is adequate; flushing may stop
B. Velocity is below 3 ft/s; continue until 1.5 m/s achieved
C. Flow must reach 3.7 m³/min (1 000 gpm) minimum
D. Flushing must continue until effluent is clear per §10.14.3.2
Answer: D. Flushing must continue until effluent is clear per §10.14.3.2
Solution: Code requires clear water, not a specific flow rate. Velocity rules (B) apply to
cleaning devices, not flushing. Arbitrary 1 000 gpm (C) is not cited.
Question 8
Which type of valve is prohibited from being installed in a private fire service main?
pg. 3
QUESTIONS!!
Introduction
This simulated examination replicates the scope, depth, and cognitive level of the NFPA
24 (Standard for the Installation of Private Fire Service Mains and Their Appurtenances)
TFM10 certification assessment. The test evaluates competency in underground pipe
installation, fire-hydrant placement, valve and appurtenance requirements, material
specifications, trenching and backfill practices, and acceptance testing/flushing
protocols. All items align with the 2022 edition of NFPA 24 and are designed to support
mastery-level performance on the actual certification exam.
General Instructions
• Read each scenario carefully; select the ONE best answer.
• Each correct response is supported by a concise code citation and rationale.
• The exam length matches the live TFM10 format: 60 questions (all scored).
• Marking criteria: +1 for each correct answer; 0 for incorrect.
• Passing score and weighting follow current NFPA/ProBoard policies (consult
your exam bulletin).
Exam Items
Question 1
A 200-mm (8 in.) private fire service main is being installed under a reinforced concrete
roadway. The trench bottom is undisturbed clay that is level and smooth. The pipe is
cement-lined ductile-iron. Which statement about bedding is correct?
A. A 100 mm sand bedding is required under the full length of pipe
B. Bedding is not required because the clay is non-settling
C. A 150 mm layer of crushed stone is mandatory for corrosion protection
D. Bedding must be placed to provide uniform support along the barrel excluding the
bell
Answer: D. Bedding must be placed to provide uniform support along the barrel
excluding the bell
Solution: NFPA 24 (2022) §6.2.2.1 requires uniform bedding support; bells are left
pg. 1
,unsupported to prevent point loading. Bedding material is required regardless of native
soil (A, B incorrect) and crushed stone alone (C) is not mandated.
Question 2
During installation, a 150 mm PVC fire main is exposed to ambient temperature of 4 °C.
After pressure testing, the pipeline must be:
A. Buried immediately to prevent freezing
B. Kept pressurized until backfill to prevent uplift
C. Drained completely before nightfall
D. Insulated with heat trace prior to test water introduction
Answer: B. Kept pressurized until backfill to prevent uplift
Solution: §7.2.5.1 allows shallow bury in cold climates if pipe remains pressurized to
resist flotation and ice expansion. Draining (C) wastes test water and time; insulation
(D) is not required by code.
Question 3
A contractor proposes locating a post-indicator valve (PIV) 2.1 m (7 ft) above the
finished grade for ease of operation. What is required by NFPA 24?
A. Acceptable if handle is accessible from a permanent platform
B. Acceptable if the valve is frost-proof
C. Not acceptable; maximum height is 1.2 m (4 ft)
D. Acceptable if an extension stem is installed to bring handle to 1.1 m
Answer: D. Acceptable if an extension stem is installed to bring handle to 1.1 m
Solution: §6.3.5.3 limits operating nut height to 0.3–1.1 m (12–42 in.). Extension stems
(D) are the compliant solution; platforms (A) are not addressed as substitutes.
Question 4
Which depth of cover is the minimum acceptable for a 200 mm ductile-iron fire service
main under an unimproved parking lot subject to light-truck traffic?
A. 0.45 m (18 in.)
B. 0.6 m (24 in.)
C. 0.75 m (30 in.)
D. 0.9 m (36 in.)
Answer: C. 0.75 m (30 in.)
Solution: Table 6.4.1.1 requires 30 in. minimum cover for pipe sizes ≥6 in. under light
vehicular loads. Lesser depths (A, B) are only permitted under sidewalks or with
concrete caps.
pg. 2
, Question 5
After final installation, a 300 m section of 150 mm cement-lined ductile-iron main is
hydrostatically tested. What is the minimum test pressure and duration?
A. 1.5 × working pressure for 30 min
B. 13.8 bar (200 psi) for 2 h
C. 13.8 bar (200 psi) or 1.5 × working pressure, whichever is greater, for 2 h
D. 20.7 bar (300 psi) for 1 h
Answer: C. 13.8 bar (200 psi) or 1.5 × working pressure, whichever is greater, for 2
h
Solution: §10.10.2.2.1 specifies the greater of 200 psi or 1.5 × working pressure for 2 h.
Option A duration is too short; 300 psi (D) is not required.
Question 6
A fire hydrant is installed on an 8 in. main. The hydrant has one 4½ in. pumper outlet
and two 2½ in. hose outlets. What is the minimum nominal diameter of the buried
hydrant lead?
A. 4 in.
B. 6 in.
C. 8 in.
D. 3 in.
Answer: B. 6 in.
Solution: §6.5.2.1 requires hydrant leads to be at least 6 in. nominal diameter to ensure
adequate flow regardless of main size.
Question 7
During flushing of a new 250 mm main, the contractor obtains a flow of 3.2 m³/min
(850 gpm) with a pitot pressure of 1.0 bar (14.5 psi) at a 64 mm (2½ in.) outlet. Which
statement is correct?
A. Flow is adequate; flushing may stop
B. Velocity is below 3 ft/s; continue until 1.5 m/s achieved
C. Flow must reach 3.7 m³/min (1 000 gpm) minimum
D. Flushing must continue until effluent is clear per §10.14.3.2
Answer: D. Flushing must continue until effluent is clear per §10.14.3.2
Solution: Code requires clear water, not a specific flow rate. Velocity rules (B) apply to
cleaning devices, not flushing. Arbitrary 1 000 gpm (C) is not cited.
Question 8
Which type of valve is prohibited from being installed in a private fire service main?
pg. 3
