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NC Fire Sprinkler practice questions

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Question 1Fire Sprinkler System Design and Installation Standards

Under NFPA 13, what is the minimum nominal pipe size for underground mains supplying a fire sprinkler system where the pipe is not run in a tunnel or covered by a building?

  1. 4 in.
  2. 3 in.
  3. 6 in. Correct answer.
  4. 2 in.

Explanation

NFPA 13 requires underground mains feeding sprinkler systems to be at least 6 in. nominal unless they run under a building or in a tunnel, where smaller sizes are permitted. The 6 in. minimum supports flow capacity and reduces the chance of blockage from sediment.

Question 2Fire Sprinkler System Design and Installation Standards

A light hazard occupancy has a design area of 1,500 sq ft using 1/2 in. sprinklers. Per NFPA 13 density/area curves, which density range applies to this design area?

  1. 0.15 gpm over the design area
  2. 0.20 gpm over the design area
  3. 0.05 gpm over the design area
  4. 0.10 gpm over the design area Correct answer.

Explanation

For light hazard, the density/area curve starts at 0.10 gpm/ft² at 1,500 sq ft and increases as design area decreases. Selecting the correct point on the curve ensures adequate water delivery for the hazard.

Question 3Fire Sprinkler System Design and Installation Standards

What is the maximum allowable spacing between sprinklers on branch lines for light hazard occupancies with standard spray upright sprinklers?

  1. 18 ft
  2. 20 ft
  3. 15 ft Correct answer.
  4. 12 ft

Explanation

NFPA 13 permits maximum sprinkler spacing of 15 ft for light hazard standard spray sprinklers, with the area per sprinkler limited to 225 sq ft. Exceeding this spacing risks inadequate coverage between heads.

Question 4Fire Sprinkler System Design and Installation Standards

A sprinkler is installed 6 in. below a combustible ceiling with structural members 10 in. deep. What is the minimum distance the deflector must be below the ceiling?

  1. 1 in.
  2. 4 in.
  3. 12 in.
  4. 6 in. Correct answer.

Explanation

Where sprinklers are installed below combustible ceilings with deep structural members, NFPA 13 requires the deflector to be at least 6 in. below the ceiling to avoid obstructions and allow proper spray development.

Question 5Fire Sprinkler System Design and Installation Standards

Which component is required at the connection between a fire department connection and the sprinkler system to prevent backflow?

  1. A pressure relief valve
  2. A check valve Correct answer.
  3. A gate valve
  4. A flow switch

Explanation

A check valve at the fire department connection prevents water from flowing backward out of the system when the FDC is not in use. This protects the public water supply and maintains system pressure.

Question 6Fire Sprinkler System Design and Installation Standards

A wet-pipe system serves an area subject to freezing. What is the minimum temperature the space must be maintained at to avoid pipe freezing per NFPA 13?

  1. 40°F Correct answer.
  2. 32°F
  3. 50°F
  4. 60°F

Explanation

NFPA 13 requires wet-pipe systems to be maintained at 40°F or higher to prevent freezing. Spaces that cannot be reliably heated must use dry-pipe or other alternatives.

Question 7Fire Sprinkler System Design and Installation Standards

How many sprinklers are typically required on a single branch line in a light hazard system before the line must be connected to a cross main?

  1. 12
  2. 10
  3. 6
  4. 8 Correct answer.

Explanation

NFPA 13 generally limits branch lines to 8 sprinklers per line in light hazard occupancies, though exceptions exist for special configurations. This limit helps balance hydraulic performance and reliability.

Question 8Fire Sprinkler System Design and Installation Standards

What is the purpose of a main drain valve on a sprinkler riser?

  1. To supply water to the FDC
  2. To drain the system for maintenance and repairs Correct answer.
  3. To regulate system pressure
  4. To test the water flow alarm

Explanation

The main drain valve allows the system to be drained for maintenance, repairs, or winterization. It is also used in the main drain flow test to verify water supply capacity.

Question 9Fire Sprinkler System Design and Installation Standards

A storage occupancy with Class IV commodities stored to 20 ft requires which sprinkler design density per NFPA 13?

  1. 0.45 gpm/ft² over 2,500 sq ft Correct answer.
  2. 0.30 gpm/ft² over 2,500 sq ft
  3. 0.20 gpm/ft² over 2,000 sq ft
  4. 0.60 gpm/ft² over 2,000 sq ft

Explanation

Class IV commodities stored up to 20 ft generally require approximately 0.45 gpm/ft² over a 2,500 sq ft design area under NFPA 13 storage criteria. Higher densities apply as storage height increases.

Question 10Fire Sprinkler System Design and Installation Standards

What is the minimum required clearance between the deflector of a standard spray sprinkler and the top of storage in a warehouse?

  1. 36 in.
  2. 12 in.
  3. 18 in. Correct answer.
  4. 6 in.

Explanation

NFPA 13 requires at least 18 in. of clearance between the sprinkler deflector and the top of storage to allow the spray pattern to develop and reach the fire.

Question 11Fire Sprinkler System Design and Installation Standards

Which type of sprinkler is designed to activate independently at a lower temperature than adjacent sprinklers, allowing faster response to a fire?

  1. Standard-response sprinkler
  2. Deluge sprinkler
  3. Quick-response sprinkler Correct answer.
  4. Open sprinkler

Explanation

Quick-response sprinklers use a smaller thermal element and respond faster to fire conditions, improving life safety and reducing water damage. They are often required in light hazard and residential occupancies.

Question 12Fire Sprinkler System Design and Installation Standards

In a dry-pipe system, what is the maximum allowable air pressure maintained in the system relative to the water supply pressure?

  1. At least 20 psi below the water supply pressure
  2. At least 20 psi above the water supply pressure Correct answer.
  3. 20 psi above the trip pressure
  4. Equal to the water supply pressure

Explanation

Dry-pipe systems maintain air pressure at least 20 psi above the water supply pressure so the dry pipe valve stays closed. This differential ensures the valve trips only when a sprinkler opens and releases air.

Question 13Fire Sprinkler System Design and Installation Standards

What is the maximum travel distance from the farthest sprinkler to the inspector's test connection in a sprinkler system?

  1. 150 ft
  2. 50 ft
  3. 200 ft
  4. 100 ft Correct answer.

Explanation

NFPA 13 requires the inspector's test connection to be located so the farthest sprinkler is no more than 100 ft of pipe away. This ensures the test simulates the flow of a single sprinkler.

Question 14Fire Sprinkler System Design and Installation Standards

A building has a combustible concealed space with wood joists spaced 24 in. on center. Which sprinkler installation is required in this space?

  1. Sprinklers required only if the space exceeds 60 in.
  2. No sprinklers required if the space is under 36 in.
  3. Sprinklers required only at the ends of joist channels
  4. Sprinklers required throughout the concealed space Correct answer.

Explanation

NFPA 13 requires sprinklers in combustible concealed spaces with wood joists unless specific exceptions apply, such as noncombustible construction or limited access. The 24 in. joist spacing does not eliminate the requirement.

Question 15Fire Sprinkler System Design and Installation Standards

What is the minimum water supply duration required for a light hazard sprinkler system?

  1. 90 minutes
  2. 120 minutes
  3. 60 minutes
  4. 30 minutes Correct answer.

Explanation

NFPA 13 requires a minimum 30-minute water supply duration for light hazard occupancies. Higher hazard classifications require longer durations.

Question 16Fire Sprinkler System Design and Installation Standards

Which valve is required on the supply side of a sprinkler system riser to indicate open or closed position?

  1. An outside screw and yoke gate valve with a supervisory switch Correct answer.
  2. A check valve with a pressure gauge
  3. A butterfly valve without a tamper switch
  4. A gate valve with a position indicator

Explanation

NFPA 13 requires a listed indicating control valve, such as an OS&Y gate valve, that supervises the open position. This ensures the valve cannot be inadvertently closed without notification.

Question 17Fire Sprinkler System Design and Installation Standards

What is the purpose of a pressure reducing valve in a sprinkler system?

  1. To increase pressure for upper floors
  2. To prevent backflow to the public supply
  3. To reduce downstream pressure to a safe level for system components Correct answer.
  4. To drain the system after testing

Explanation

Pressure reducing valves limit downstream pressure to protect sprinkler components and piping from excessive pressure. They are required where supply pressure exceeds the system's rated working pressure.

Question 18Fire Sprinkler System Design and Installation Standards

A sprinkler system has a design area of 2,500 sq ft and a density of 0.15 gpm/ft². What is the minimum required flow?

  1. 375 gpm Correct answer.
  2. 500 gpm
  3. 300 gpm
  4. 250 gpm

Explanation

Required flow equals density multiplied by design area: 0.15 gpm/ft² × 2,500 sq ft = 375 gpm. This flow must be available at the required residual pressure.

Question 19Fire Sprinkler System Design and Installation Standards

What is the maximum allowable distance between the sprinkler deflector and the ceiling for a standard spray pendent sprinkler?

  1. 18 in.
  2. 6 in.
  3. 8 in.
  4. 12 in. Correct answer.

Explanation

NFPA 13 permits standard spray pendent sprinklers to be installed with the deflector up to 12 in. below the ceiling, provided the spacing and obstruction rules are met. Greater distances require special consideration.

Question 20Fire Sprinkler System Design and Installation Standards

In a deluge system, which component initiates the release of water to all open sprinklers?

  1. A check valve
  2. Individual sprinkler thermal elements
  3. A detection system or manual pull station Correct answer.
  4. A pressure relief valve

Explanation

Deluge systems use open sprinklers and rely on a detection system or manual release to open the deluge valve, flooding all heads simultaneously. This is suited to high-hazard areas where rapid water application is critical.

Question 21Fire Sprinkler System Design and Installation Standards

A sprinkler is located in a room with a sloped ceiling having a slope of 4 in 12. Where must the sprinkler be positioned relative to the peak?

  1. At the peak only
  2. Within 3 ft of the peak Correct answer.
  3. At the low point of the slope
  4. Anywhere within the room

Explanation

For sloped ceilings, NFPA 13 requires sprinklers to be positioned within 3 ft of the peak to ensure coverage of the highest point where heat collects. Additional sprinklers may be needed based on the slope.

Question 22Fire Sprinkler System Design and Installation Standards

What is the minimum size of the bypass around a pressure reducing valve in a sprinkler system?

  1. 2 in.
  2. 1/2 in.
  3. 1 in.
  4. 3/4 in. Correct answer.

Explanation

NFPA 13 requires a bypass around pressure reducing valves to be at least 3/4 in. to allow water flow during maintenance. The bypass ensures the system remains operational.

Question 23Fire Sprinkler System Design and Installation Standards

Which of the following is the correct method for hydrostatically testing a new sprinkler system?

  1. Test at normal working pressure for 1 hour
  2. Test at 200 psi for 2 hours Correct answer.
  3. Test at 50 psi above normal working pressure for 2 hours
  4. Test at 100 psi for 4 hours

Explanation

NFPA 13 requires a hydrostatic test at 200 psi for 2 hours unless the working pressure exceeds 150 psi, in which case the test pressure is 50 psi above working pressure. This verifies system integrity before acceptance.

Question 24Fire Sprinkler System Design and Installation Standards

What is the purpose of an antifreeze loop in a sprinkler system?

  1. To increase water pressure
  2. To detect water flow
  3. To reduce pipe corrosion
  4. To protect exposed piping in freezing areas Correct answer.

Explanation

Antifreeze loops protect portions of piping exposed to freezing temperatures by circulating a glycol solution. They are used where wet-pipe systems cannot be fully heated.

Question 25Fire Sprinkler System Design and Installation Standards

A sprinkler system has a 4 in. riser and a 2 in. branch line. What is the minimum required drain size at the low point of the system?

  1. 3 in.
  2. 4 in.
  3. 1 in.
  4. 2 in. Correct answer.

Explanation

NFPA 13 requires the main drain to be sized to allow rapid draining of the system, typically at least the size of the largest branch line or 2 in. minimum. This ensures efficient maintenance and winterization.

Question 26Fire Sprinkler System Design and Installation Standards

Under NFPA 13, what is the minimum nominal pipe size for the main drain connection on a riser serving a system with a 2 in. riser?

  1. 1 in.
  2. 2 in. Correct answer.
  3. 1 1/4 in.
  4. 3/4 in.

Explanation

NFPA 13 requires the main drain valve and its piping to be sized based on the riser size, and for risers of 2 in. and larger the main drain must be a minimum of 2 in. nominal. The drain must be capable of discharging the system's flow at a rate that allows the water supply test to be performed accurately. Smaller drains cannot pass enough water to validate the supply curve.

Question 27Fire Sprinkler System Design and Installation Standards

Which component is required at the connection between a municipal water supply and a sprinkler system to prevent backflow of stagnant sprinkler water into the potable supply?

  1. A check valve at the riser
  2. A waterflow switch on the riser
  3. An approved backflow prevention assembly Correct answer.
  4. A pressure relief valve downstream of the riser

Explanation

NFPA 13 and plumbing codes require an approved backflow prevention assembly where a sprinkler system connects to a potable public water supply. A simple check valve does not provide the same protection against backsiphonage and backpressure. The assembly must be listed and installed per the authority having jurisdiction.

Question 28Fire Sprinkler System Design and Installation Standards

A light hazard occupancy has a design area of 1,500 sq ft. Using the density/area method with a 0.10 gpm/ft² density, what is the minimum sprinkler demand at the base of the riser before hose allowance?

  1. 250 gpm
  2. 1,500 gpm
  3. 150 gpm Correct answer.
  4. 100 gpm

Explanation

The required sprinkler flow is the design density multiplied by the design area: 0.10 gpm/ft² × 1,500 sq ft = 150 gpm. Hose stream allowance is added separately on top of this figure. This calculation establishes the sprinkler demand that the water supply must satisfy.

Question 29Fire Sprinkler System Design and Installation Standards

Which standard governs the installation of residential sprinkler systems in one- and two-family dwellings and manufactured homes?

  1. NFPA 13
  2. NFPA 13D Correct answer.
  3. NFPA 13R
  4. NFPA 14

Explanation

NFPA 13D is the standard for the installation of sprinkler systems in one- and two-family dwellings and manufactured homes. NFPA 13R covers low-rise residential occupancies up to and including four stories. NFPA 13 is the general commercial standard, and NFPA 14 covers standpipe systems.

Question 30Fire Sprinkler System Design and Installation Standards

In a hydraulically calculated system, what does the term 'safety margin' represent when applied to the water supply curve?

  1. The extra pressure added to account for future occupancy changes
  2. The difference between the available supply pressure and the calculated system demand at the design point Correct answer.
  3. The amount by which the static pressure exceeds the residual pressure
  4. The pressure lost through the backflow preventer only

Explanation

The safety margin is the cushion between what the water supply can deliver at the design flow and what the system actually requires at that point. NFPA 13 permits a credit for this margin under specified conditions when evaluating the supply. It protects against supply fluctuations and calculation uncertainties.

Question 31Fire Sprinkler System Design and Installation Standards

What is the maximum allowable spacing between sprinklers on a branch line for a light hazard, standard spray upright sprinkler installation under NFPA 13?

  1. 12 ft
  2. 10 ft
  3. 15 ft Correct answer.
  4. 20 ft

Explanation

For light hazard occupancies with standard spray sprinklers, NFPA 13 limits maximum spacing to 15 ft between sprinklers and 15 ft from the end sprinkler to the wall. Protection area per sprinkler is also capped. Larger spacings are permitted only for specific sprinkler types such as extended coverage.

Question 32Fire Sprinkler System Design and Installation Standards

A sprinkler system must be hydrostatically tested. Which pressure and duration satisfy the NFPA 13 requirement for a new system?

  1. 100 psi for 1 hour
  2. 50 psi for 24 hours
  3. 200 psi for 2 hours Correct answer.
  4. 150 psi for 30 minutes

Explanation

NFPA 13 requires new sprinkler systems to be hydrostatically tested at 200 psi for 2 hours, or at 50 psi above the normal working pressure if that exceeds 200 psi. The test verifies joint integrity before the system is placed in service. The pressure is measured at the low point of the system.

Question 33Fire Sprinkler System Design and Installation Standards

Which condition requires the installation of sprinklers in a concealed space with combustible construction under NFPA 13?

  1. The space is less than 6 in. in height
  2. The space is protected by a smoke detection system
  3. The concealed space contains combustible materials and exceeds the dimensional limits that would otherwise exempt it Correct answer.
  4. The concealed space is constructed of noncombustible materials with no combustible storage

Explanation

NFPA 13 exempts certain concealed spaces of limited size and noncombustible construction from sprinkler protection. When the space contains combustible materials or exceeds those dimensional limits, sprinklers must be installed. Detection systems do not substitute for sprinkler protection in these spaces.

Question 34Fire Sprinkler System Design and Installation Standards

In a dry-pipe system, what is the maximum time allowed for water to reach the most remote sprinkler after the dry pipe valve trips, measured from the test connection?

  1. 90 seconds
  2. 120 seconds
  3. 30 seconds
  4. 60 seconds Correct answer.

Explanation

NFPA 13 requires the dry pipe valve to deliver water to the test connection at the most remote sprinkler within 60 seconds of the valve tripping. This limit ensures the system responds quickly enough to control a fire. Exceeding it typically requires correction such as adjusting air pressure or adding a quick-opening device.

Question 35Fire Sprinkler System Design and Installation Standards

A designer is laying out sprinklers beneath a smooth, flat ceiling with a 12 ft ceiling height in an ordinary hazard occupancy. Which deflector position relative to the ceiling is acceptable for a standard spray pendent sprinkler?

  1. At least 36 in. below the ceiling
  2. Flush against the ceiling
  3. At least 18 in. below the ceiling
  4. Between 1 in. and 12 in. below the ceiling Correct answer.

Explanation

For standard spray pendent sprinklers under a smooth flat ceiling, the deflector must be positioned within the range specified in NFPA 13, generally 1 in. to 12 in. below the ceiling for standard spray sprinklers. Positioning too close or too far affects the spray pattern and coverage. The exact range depends on sprinkler type and listing.

Question 36Fire Sprinkler System Design and Installation Standards

Which of the following best describes the role of the authority having jurisdiction in the approval of a sprinkler system design?

  1. The AHJ reviews and approves plans and may require additional protection beyond the standard Correct answer.
  2. The AHJ sets the water supply pressure for the municipal main
  3. The AHJ performs the hydraulic calculations on behalf of the designer
  4. The AHJ manufactures the sprinkler heads used in the system

Explanation

The AHJ is responsible for reviewing plans and specifications and determining compliance with the applicable codes and standards. The AHJ may also require protection exceeding the minimum standard where conditions warrant. The AHJ does not perform the design calculations or manufacture equipment.

Question 37Fire Sprinkler System Design and Installation Standards

A high-piled storage area with Class III commodities is being evaluated. Which factor most directly determines the required sprinkler design density under NFPA 13?

  1. The number of employees in the building
  2. The color of the packaging material
  3. The storage height and the commodity classification Correct answer.
  4. The building's exterior wall construction

Explanation

Design density for storage occupancies depends primarily on commodity classification and storage height, along with aisle width and sprinkler type. Higher storage and more hazardous commodities require greater density. Packaging color and occupant counts do not drive density selection.

Question 38Fire Sprinkler System Design and Installation Standards

A sprinkler system uses a wet-pipe riser with a 6 in. main drain. During a main drain flow test, the residual pressure at the riser drops significantly below the static pressure. What does this most likely indicate?

  1. The system has a closed valve downstream of the test connection
  2. The water supply is restricted or the drain is flowing at a rate that reveals a limited supply Correct answer.
  3. The backflow preventer is leaking
  4. The sprinkler heads are oversized

Explanation

A large drop between static and residual pressure during a main drain test indicates a restricted or limited water supply. The test compares static pressure with the pressure while water flows through the drain. A significant drop points to supply problems that must be investigated.

Question 39Fire Sprinkler System Design and Installation Standards

Two sprinkler systems share a common water supply. Under NFPA 13, what is required regarding the hydraulic calculations when systems are interconnected?

  1. The systems must be combined into a single zone regardless of size
  2. The calculations must account for the simultaneous demand of interconnected systems where required Correct answer.
  3. Each system may be calculated independently with no consideration of the other
  4. Only the larger system requires calculation

Explanation

When systems are interconnected and can demand water simultaneously, the hydraulic calculations must consider the combined demand to ensure adequate supply. Ignoring the other system can result in an undersized supply. The specific simultaneous demand requirements depend on the arrangement and applicable code provisions.

Question 40Fire Sprinkler System Design and Installation Standards

In a deluge system protecting a special hazard, which feature distinguishes its sprinklers from those in a wet-pipe system?

  1. The sprinklers use a heat-responsive glass bulb
  2. The sprinklers are open and discharge water when the deluge valve opens Correct answer.
  3. The sprinklers are charged with air until activated
  4. The sprinklers have fusible links that operate individually

Explanation

Deluge systems use open sprinklers with no heat-responsive element; all discharge simultaneously when the deluge valve is actuated by a detection system. Wet-pipe sprinklers operate individually via fusible links or glass bulbs. This design floods the entire protected area at once.

Question 41Fire Sprinkler System Components and Materials

A fire department connection on a sprinkler system is intended to serve which primary purpose?

  1. Supply domestic water to the building's plumbing fixtures
  2. Supplement the automatic water supply during a fire Correct answer.
  3. Serve as the only water source for the system
  4. Provide a drain for the riser during hydrostatic testing

Explanation

The fire department connection lets pumper apparatus augment the system's supply when the automatic source is inadequate or during a large fire demand. It is a supplemental feed, not a substitute for the automatic supply required by design. Testing drains and domestic plumbing are separate systems entirely.

Question 42Fire Sprinkler System Components and Materials

In a wet-pipe sprinkler system, the alarm check valve serves which function?

  1. It automatically drains the system after each flow
  2. It prevents water from entering the sprinkler piping until a fire is detected
  3. It holds system pressure and directs water to the alarm line when flow occurs Correct answer.
  4. It regulates the pressure of the public water main

Explanation

The alarm check valve is a check valve that keeps water in the system and, when flow lifts the clapper, routes water to the water motor gong or alarm pressure switch. It is not a dry-pipe valve, so water is already present in the piping. It does not drain the system or regulate the street main.

Question 43Fire Sprinkler System Components and Materials

Which sprinkler characteristic is identified by the temperature rating marked on the deflector or link?

  1. The temperature at which the deflector begins to deform
  2. The maximum ceiling temperature the sprinkler can survive
  3. The temperature at which the heat-responsive element operates Correct answer.
  4. The temperature of the water supply required for the system

Explanation

The temperature rating stamped on a sprinkler is the operating temperature of its heat-responsive element, such as a fusible link or glass bulb. Selection is based on the expected ceiling temperature, with a margin above it. The rating does not describe water supply temperature or deflector deformation.

Question 44Fire Sprinkler System Components and Materials

A sprinkler head installed in a concealed space between a suspended ceiling and the floor above, where the ceiling is not a required rated assembly, must generally be what type?

  1. Upright Correct answer.
  2. Concealed
  3. Pendent
  4. Sidewall

Explanation

Upright sprinklers are the standard choice for unprotected combustible concealed spaces because they protect the space above the ceiling. Pendent and sidewall heads are designed for the occupied room below. Concealed sprinklers are used where appearance in the room matters, not for the hidden void.

Question 45Fire Sprinkler System Components and Materials

What is the function of a retard chamber on a wet-pipe alarm check valve?

  1. It delays the alarm signal so small pressure fluctuations do not cause false alarms Correct answer.
  2. It prevents water from reaching the alarm pressure switch
  3. It slows the flow of water to the sprinklers during the first minute of a fire
  4. It stores water for the main drain test

Explanation

The retard chamber absorbs brief pressure surges in the system so the water motor gong or pressure switch does not sound an alarm for minor fluctuations. It is an alarm-line device, not part of the sprinkler discharge path. It does not store test water or block the alarm switch.

Question 46Fire Sprinkler System Components and Materials

Which piping material is permitted for underground fire service mains where approved for the application?

  1. Ductile iron Correct answer.
  2. Copper tube
  3. Galvanized steel only
  4. Black steel

Explanation

Ductile iron pipe is a standard material for underground fire mains and is listed for that service. Galvanized and black steel and copper are used above ground; their use underground is restricted because of corrosion concerns. The question tests recognition of an approved underground material.

Question 47Fire Sprinkler System Components and Materials

The deflector of a pendent sprinkler is designed to do what?

  1. Direct all water straight down in a single stream
  2. Break the water stream into a controlled spray pattern Correct answer.
  3. Filter debris from the water supply
  4. Prevent water from hitting the ceiling

Explanation

The deflector distributes water into a designed spray pattern that provides the required coverage and density. It does not create a single stream, and it cannot prevent splash onto the ceiling. It also has no filtering function.

Question 48Fire Sprinkler System Components and Materials

A dry-pipe valve is used in a dry-pipe system because it performs which function?

  1. It mixes antifreeze with the water supply
  2. It automatically drains the system after each activation
  3. It keeps the system piping filled with air or nitrogen under pressure and admits water only when a sprinkler operates Correct answer.
  4. It heats the system piping to prevent freezing

Explanation

The dry-pipe valve holds air or nitrogen pressure in the piping above the valve and opens to admit water when a sprinkler operates and releases that pressure. This keeps water out of unheated piping so it cannot freeze. It does not heat, drain, or mix antifreeze.

Question 49Fire Sprinkler System Components and Materials

A sprinkler is installed in a room with a ceiling temperature that can reach 130°F. What is the minimum temperature rating generally selected for the sprinkler?

  1. 175°F
  2. 155°F Correct answer.
  3. 200°F
  4. 135°F

Explanation

Sprinkler temperature ratings are chosen with a margin above the maximum expected ceiling temperature, commonly about 25°F above it. With a 130°F ceiling, a 155°F rated sprinkler satisfies that margin. A 135°F rating is too close to the ambient temperature and risks premature operation.

Question 50Fire Sprinkler System Components and Materials

During a main drain test on a wet-pipe riser, the static pressure reads 80 psi and the residual pressure during flow reads 62 psi. What does this result most directly indicate?

  1. The water supply is adequate and the main drain is flowing Correct answer.
  2. The alarm check valve is stuck open
  3. The fire department connection is leaking
  4. The sprinkler system has a closed control valve

Explanation

A main drain test compares static and residual pressure with the main drain flowing fully. A drop of this magnitude shows water is flowing and the supply is delivering, which is the normal result of a passing test. It does not by itself indicate a stuck valve, a closed control valve, or an FDC leak.