Automatic Sprinkler Systems CEU 242 - Welcome to ASPE · National Fire Protection Association...

CEU

242

Automatic Sprinkler Systems

Continuing Education from the American Society of Plumbing Engineers

December 2016

ASPE.ORG/ReadLearnEarn

National Fire Protection Association (NFPA) 13: Standard for the Installation of Sprinkler Systems provides the minimum requirements for the design and installation of automatic fire sprinkler systems, but it also allows for alternate design approaches and system components. When designing such systems, it is important to follow all of the requirements in NFPA 13, so verify with the local authority having jurisdiction (AHJ) which edition should be used.

HISTORY OF FIRE SPRINKLERSThe first sprinkler system in the United States was installed in 1852 and consisted of perforated pipe. The first automatic sprinkler was invented 12 years later to control, confine, and extinguish fires to prevent the loss of life and minimize the loss of property. By 1895, sprinkler system development was increasing significantly, and the Boston area alone had nine different systems. Boston experienced the most growth in this discipline because of the number of hazardous textile mills in the area.

Before 1950, sprinkler heads simultaneously discharged water upward and downward. The downward discharge quenched the fire, while the upward discharge kept the structure cool. These inefficient heads were subsequently re-placed by upright and pendent heads. NFPA 13NFPA 13 was first written in 1896. It was prepared in conjunction with fire service personnel, fire insurance represen-tatives, laboratories that tested fire protection items, representatives from fire protection equipment manufacturers, contractors who installed such systems, and consulting engineers who specified and designed these systems. Since then, the standard has evolved significantly, especially in 1997 when it was expanded to include design and installa-tion information from more than 40 other NFPA standards. The current edition of NFPA 13 includes design criteria for underground pipe, rack storage, high-piled storage, and other unique hazards.

With the unprecedented development of sprinkler system devices, installation practices, and design techniques for automatic sprinkler systems, increased diligence is required when designing and installing these systems, as the re-quirements have become both more complex and less uniform. As with any other code or standard, NFPA 13 gives only the minimum requirements to provide a reasonable degree of protection. Based on the owner’s preference, additional protection may be installed for a higher degree of safety.

FIRE SPRINKLER SYSTEM DESIGNWhen designing a fire sprinkler system, the following items should be considered:

• Basis of the design• Type of system to be selected• Occupancy classification• Materials to be specified• Basic installation requirements• Hanging and restraint requirements• Design approaches• System acceptanceIt is essential to design a sprinkler system to fit the particular hazard of a building or structure. NFPA 13 includes

requirements for general storage, high-piled and rack storage, plastic and rubber commodities storage, and other special occupancies. (Note: Requirements for storage occupancies and certain special sprinklers are not included in the scope of this chapter.) Basis of DesignThe first step in designing a fire sprinkler system is to ask the owner to complete an owner’s information certificate, which can be found in NFPA 13. This certificate informs the designer and installer of the owner’s intended occupancy of the building, including what materials will be used and how they will be stored, preliminary construction plans of the building, and any environmental concerns, such as the possibility of microbiologically influenced corrosion (MIC).

Reprinted from Fire Protection Systems, Third Edition. © 2016, American Society of Plumbing Engineers. All rights reserved.

Note: In determining your answers to the CE questions, use only the material presented in the corresponding continuing education article. Using information from other materials may result in a wrong answer.

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Once the designer understands the construction and intended use of the building, design documents consisting of drawings, calculations, and specifications can be prepared. These documents must be approved and kept readily avail-able for further inspection and modifications if necessary. Sprinkler System TypesThe factors to consider in selecting the type of sprinkler system or the type of suppression system are:

• Types of building construction and contents needing protection• The potential of a fast-growing

fire developing• Valuable items in the area being

protected that would be damaged by water

• The freezing potential of the area being protected

Knowing this information will help determine the type of suppression sys-tem to be designed and installed. The various types of fixed sprinkler systems are clearly defined in NFPA 13 and sum-marized below.Wet Pipe SystemsA wet pipe system (see Figure 9-1) em-ploys automatic sprinklers attached to a piping network containing water under pressure at all times. The system is connected to a water supply so water discharges immediately from the sprinklers when they open. Approxi-mately 75 percent of the sprinkler systems in use are wet pipe systems. This type of sprinkler system is easy to maintain and is considered the most reliable. It is installed where freezing or other special requirements are not a concern.Dry Pipe SystemsThe dry pipe system employs automatic sprinklers attached to a piping system containing air or nitrogen under pressure, the release of which (as from a sprinkler opening) allows the water pressure to open a valve known as a dry pipe valve (see Figure 9-2). The water then flows into the piping system and out the opened sprinklers. A dry pipe system requires more time to get water to a fire than a wet pipe system; however, the time between the sprinkler opening and the water flowing can be shortened by using quick-opening devices.

This system is used where sprinklers are subject to freezing. The dry pipe system uses compressed air from a plant supply or a local air compressor. The air supply will typically have a restrictive orifice to limit the rate at which com-pressed air is introduced into the system. The sprinkler head orifice is much larger than the air supply pipe opening, so the opening of a sprinkler head will allow the system air pressure to drop and the dry valve to open.Preaction Systems A preaction system employs automatic sprinklers that are attached to a piping system containing air that may or may not be under pressure, with a supplemental detection system installed in the same areas as the sprinklers (see Figure 9-3). Actuation of the detection system and sprinklers in the case of a double-interlocked system opens a valve, which allows water to flow into the sprinkler piping system and to be discharged from any sprinklers that may be open. This system is often used where valuables are stored and accidental water discharge may cause damage.

Figure 9-1 Wet Pipe Sprinkler System

Figure 9-2 Dry Pipe Valve(Left) Air pressure maintains clapper closed.

(Right) Venting of air allows clapper to open and water to flow.

Figure 9-3 Preaction Valve Riser


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Deluge SystemsA deluge system employs open heads attached to a piping system and is connected to a water supply through a deluge valve, which is opened by the operation of a detection system installed in the same area as the sprinklers (see Figure 9-4). When this valve opens, water flows into the piping system and discharges from all attached heads. This system is used in very high-hazard areas where rapid application of large volumes of water is required to quickly gain control of a fire.Combined Dry Pipe and Preaction Sprinkler SystemsCombined systems employ automatic sprinklers attached to a piping system con-taining air under pressure, with a supplemental detection system installed in the same area as the sprinklers. Operation of the detection system actuates tripping devices, which open dry pipe valves simultaneously and without the loss of air pressure in the system. Operation of the detection system also opens approved air exhaust valves at the end of the feed main, which usually precedes the sprinklers opening. The detection system also serves as an automatic fire alarm system.Antifreeze Systems An antifreeze system (see Figure 9-5) is a wet pipe system employ-ing automatic sprinklers attached to a piping system that contains an antifreeze solution and is connected to a water supply. The antifreeze solution fills the pipes first, followed by water, which discharges im-mediately from sprinklers that are opened by the heat from a fire. The antifreeze system is no different than a wet system except that the initial charge of water is mixed with antifreeze, so the system may be installed in unheated areas. Additional devices may be required to prevent air pocket formation.

Due to the possible combustibility of some antifreeze solutions, NFPA has been researching the use of antifreeze in wet pipe systems and updating standards as needed. Thus, it is critical to consult the latest version of the applicable standard regarding the maximum concentra-tion of antifreeze solution allowed.

OCCUPANCY CLASSIFICATIONSLight HazardLight hazard occupancies are those where the quantity and/or combustibility of contents is low and fires with relatively low rates of heat release are expected. Examples include:

• Churches• Clubs• Eaves and overhangs of combustible construction with no combustibles beneath• Educational facilities• Libraries, except for large stack rooms• Museums• Nursing or convalescent homes• Offices, including data processing areas• Restaurant seating areas• Theaters and auditoriums, excluding stages and prosceniums• Unused attics

Ordinary Hazard Group 1Ordinary Hazard Group 1 occupancies are those where combustibility is low, the quantity of combustibles is moderate, stockpiles of combustibles do not exceed 8 feet, and fires with moderate rates of heat release are expected. Examples include:

• Automobile parking lots and showrooms • Bakeries• Beverage manufacturing• Canneries

Figure 9-4 Deluge Valve Riser

Figure 9-5 Antifreeze System

1. Check valve shall be permitted to be omitted where sprinklers are below the level of valve A.

2. The 1/32-inch hole in the check valve clapper is needed to allow for expansion of the solution during a temperature rise, thus preventing damage to sprinklers.

Filing cup

Unheated area

Pitch to drainDrain valve

Check valve(1/32-inch hole

in clapper)

Water supply

Heated area

Approved indicating

valve

A

B

Non

freez

ing

solu

tion

Drop,5 feet

minimum

Water

12 inches

Wal

l



• Dairy product manufacturing and processing• Electronic plants• Glass and glass product manufacturing• Laundries• Restaurant service areas

Ordinary Hazard Group 2Ordinary Hazard Group 2 occupancies are defined as occupancies where the quantity and/or combustibility of contents is moderate to high, stockpiles of contents with moderate rates of heat release do not exceed 12 feet, and stockpiles of contents with high rates of heat release do not exceed 8 feet. Examples include:

• Cereal mills• Chemical plants (ordinary)• Distilleries• Dry cleaners• Feed mills• Horse stables• Leather goods manufacturing• Libraries with large stack rooms• Machine shops• Metal working• Paper and pulp mills• Piers and wharves• Post offices• Repair garages• Stages• Tire manufacturing

Extra Hazard Group 1Extra Hazard Group 1 occupancies are those where the quantity and combustibility of contents are very high and dust or other materials are present, introducing the probability of rapidly developing fires with high rates of heat release, but with little or no combustible or flammable liquids. Examples include:

• Aircraft hangars• Combustible hydraulic fluid use areas• Die casting• Metal extruding• Plywood and particle board manufacturing• Printing (using inks having flash points below 100°F)• Rubber reclaiming, compounding, drying, milling, and vulcanizing• Saw mills• Textile picking, opening, blending, garnetting, carding, and the combining of cotton, synthetics, wool shoddy, or

burlap• Upholstering with plastic foams

Extra Hazard Group 2Extra Hazard Group 2 occupancies have moderate to substantial amounts of flammable or combustible liquids or ex-tensive shielding of combustibles. Examples include:

• Asphalt saturating• Flammable liquid spraying• Flow coating• Mobile home or modular building assemblies (where a finished enclosure is present and has combustible interiors)• Open oil quenching• Plastic processing• Solvent cleaning• Varnish and paint dipping



COMPONENTS AND MATERIALSIn general, all components used in a sprinkler system should be listed (i.e., approved by a third-party testing agency) and used in accordance with their listing. Certain components that do not affect system performance are not required to be listed (e.g., drain valves and signs).SprinklersThe automatic sprinkler head is a thermosensitive device that is automatically activated when the area in which it is installed reaches a predetermined temperature. Once this temperature is met, the sprinkler head releases a stream of water and distributes it in a specific pattern and quantity over a designated area. Water reaches the sprinklers through a network of overhead pipes, and the sprinklers are placed along the pipes at regular, geometric intervals.

Sprinkler heads shall never be stored where temperatures may exceed 100°F. Sprinkler heads shall never be painted, coated, or modified in any way after leaving the manufacturing premises. Care should be exercised to prevent damage to sprinkler heads during handling.

The sprinkler should be selected based on the following criteria:

• Temperature ratings are based on the expected ambient ceiling temperature around the sprinkler (see Table 9-1). Where the maximum expected tem-perature is less than 100°F, ordinary temperature sprinklers should be selected. Sprinklers located in areas exposed to heat-producing devices (space heat-ers, steam mains, skylights, etc.) should have higher temperature ratings to prevent accidental operation.

• Orifice sizes are based on the available pressure and the required water flow rate. Larger K factors mean that less pressure is required to reach a given flow rate.

• Thermal sensitivity refers to how quickly a sprinkler will respond to a change in the ambient temperature. Quick-response sprinklers increase the protection of life and property and are generally required in all new light hazard occupancies. They also are often used in ordinary hazard occupancies because their faster response to a fire allows reductions in the design area, thereby resulting in smaller pipe sizes.

Sprinkler TypesStandard sprinkler heads are made for installation in an upright or pendent position and must be installed in the posi-tion for which they were constructed. Architects sometimes require special sprinkler types to be used for certain ap-plications. The many types of commercially available sprinklers include the following:

• Upright: Normally installed above the supply pipe• Pendent: Installed below the pipe• Sidewall (horizontal and vertical): Similar to standard sprinkler heads except for a special deflector, which al-

lows the discharge of water toward one side only in a pattern resembling one-quarter of a sphere. The forward horizontal range of about 15 feet is greater than that of a standard sprinkler. For special applications, a sidewall vertical type is used.

• Extended coverage: Covers more than 225 square feet per head or greater distances than standard sprinklers• Open sprinklers• Corrosion resistant: Mostly regular pendent or upright type heads used in areas where corrosive substances

are present (e.g., chlorine storage rooms and salt-water reservoirs) that are coated with wax or Teflon by the manufacturer to protect against corrosives

• Nozzles• Dry pendent and dry upright: Used where a limited enclosure is subject to freezing; may be connected to a wet

pipe system through a special dry pipe connector• Quick response (QR)• Quick response, extended coverage (QREC)• Quick response, early suppression (QRES)• Early suppression, fast response (ESFR)• Ornamental

Table 9-1 Sprinkler Temperature Ratings and Temperature Classification Color Codes

Maximum Ceiling

Temperature

Temperature Rating

Temperature Classification

Color Code (with Fusible

Link)

Glass Bulb Color

100°F 135–170°F Ordinary Uncolored or Black

Orange (135°F) or

Red (155°F)

150°F 175–225°F Intermediate WhiteYellow

(175°F) or Green (200°F)

225°F 250–300°F High Blue Blue300°F 325–375°F Extra High Red Purple

375°F 400–475°F Very Extra High Green Black

475°F 500–575°F Ultra High Orange Black625°F 650°F Ultra High Orange Black

Source: NFPA 13



• Recessed: Most of the body is mounted within a recessed housing and operation is similar to a standard pendent sprinkler

• Flush: The working parts of the sprinkler head extend below the ceiling into the area in which it is installed without affecting the heat sensitiv-ity or the pattern of water distribution

• Concealed: The entire body, including the operating mechanism, is above a cover plate, which drops when a fire occurs, exposing the thermosensitive assembly. The deflector may be fixed, or it may drop below the ceiling level when water flows.

• Residential: Designed to respond to a fire much faster than standard commercial and industrial sprinklers

• On/off sprinkler headsPipingNFPA allows the use of steel pipe, copper tube, and other specially listed pipes (see Table 9-2). The pipe selected should be based on the maximum system pressure, ambient conditions, aesthetics, and possible exposure of the pipe to fire conditions. AlarmsThree basic types of alarms can be part of a sprinkler system:

• Vane-type water flow: This alarm comes equipped with a small paddle that is inserted directly into the riser pipe (see Figure 9-6). The paddle responds to water flow as low as 10 gallons per minute (gpm), which then triggers an alarm. This type may be equipped with a delayed sys-tem (adjustable from 0 to 120 seconds) to prevent false alarms caused by normal water pressure fluctuations.

• Mechanical water flow (water motor gong): This alarm involves a check valve that lifts from its seat when water flows (see Figure 9-7). The check valve may vary as follows. The differ-ential type has a seat ring with a concentric groove connected by a pipe to the alarm device. When the clapper of the alarm valve rises to allow water to flow to the sprinklers, water enters the groove and flows to the alarm-giving device. Another type has an extension arm connected to a small auxiliary pilot valve, which, in turn, is connected to the alarm system.

• Pressure-activated alarm switch: This is used in conjunction with dry pipe valves, alarm check valves, and other types of water control valves. It has contact elements arranged to open or close an electric circuit when subjected to increased or reduced pressure. In most cases, the motion to activate a switch is given from a diaphragm exposed to pressure on one side and supported by an adjustable spring on the other side.

The alarm for a dry pipe sprinkler system is arranged with a connection from the intermediate chamber of the dry pipe valve to a pressure-operated alarm device. When the dry pipe valve trips, the intermediate chamber, typically con-taining air at atmospheric pressure, fills with water at the supply pressure, which operates the alarm devices. Sometimes both an outdoor water motor gong and a pressure-operated electric switch are provided. The alarm devices for deluge and preaction systems are the same as those used for dry pipe systems.

Codes require water supply control valves to indicate conditions that could prevent the unwanted or unnecessary operation of the sprinkler system. This can be achieved by using electric switches, also called temper switches, which can be selected for open or closed contact. The signal that indicates valve operation is given when the valve wheel is given two turns from the wide-open position. The restoration signal sounds when the valve is restored to its fully open position. This simply cancels the temper switch alarm.Other ComponentsSprinkler system components are typically designed for a minimum pressure of 175 pounds per square inch (psi). If the pressure required in the system is higher than 175 psi, then all system components must be rated for the higher pressure. It is not unusual for systems to be designed with maximum pressures of 250 to 300 psi.

Table 9-2 Approved Materials for Sprinkler System Pipe

Material Standard

Ferrous piping (welded and seamless) ASTM A795

Welded and seamless steel pipe ASTM A53

Wrought steel pipe ASME B36.10MElectric-resistance welded

steel pipe ASTM A135

Copper tube (drawn, seamless)

ASTM B42; ASTM B75

Seamless copper water tube ASTM B88Wrought seamless copper

and copper alloy tube ASTM B251

Fluxes for soldering applications of copper and

copper alloy tube ASTM B813

Brazing filler metal (classification BCuP-3 or

BCuP-4) AWS A5.8

Solder metal ASTM B32Alloy materials ASTM B446

Plastic pipe (CPVC, PEX) ASTM F442; ASTM F876

Source: NFPA 13Note: Always verify approved materials with the AHJ.

Figure 9-6 Vane-Type Water Flow Indicator

Figure 9-7 Alarm Check Valve Riser



BASIC INSTALLATION REQUIREMENTSArea LimitationsThe maximum floor area that may be protected by sprinklers supplied on each system riser on any one floor is as follows:

• Light hazard: 52,000 square feet• Ordinary hazard: 52,000 square

feet• High-piled storage: 40,000 square

feet• Extra hazard, pipe schedule:

25,000 square feet• Extra hazard, hydraulically calcu-

lated: 40,000 square feetSpacing per Sprinkler Head and Between Sprinkler HeadsThe maximum spacing for standard pendent and upright sprinklers is shown in Table 9-3. Other sprinklers, such as sidewalls, extended coverage, control mode specific application (CMSA), ESFR, and residential sprinklers have different rules, and NFPA 13 and the specific listings of each sprinkler should be consulted for proper design and installation methods.Deflector PositionsUnder unobstructed construction, the sprinkler deflector should be a minimum of 1 inch and a maximum of 12 inches below the ceiling. Under obstructed construction, the sprinkler deflector should be located in a horizontal plane between 1 inch and 6 inches below the structural members and a maximum distance of 22 inches below the ceiling/roof deck.Obstructions to Sprinkler DischargeNFPA 13 contains numerous figures and tables to clarify where obstructions are considered too significant and could cause sprinklers to provide inadequate coverage. These rules apply to obstructions such as beams, soffits, privacy partitions, joists, ducts, lights, etc. In general, sprinklers should be located to minimize obstructions to discharge, or additional sprinklers should be provided to ensure adequate coverage.

The rule commonly known as the “three times rule” states that a sprinkler located within 24 inches of an obstruction should be located a distance at least three times the maximum dimension of the obstruction. For example, a sprinkler located near a 4-inch wide by 4-inch deep obstruction should be located at least 12 inches from the obstruction.

In general, sprinkler deflectors should be located 18 inches above storage or other obstructions that could interrupt the discharge pattern of the sprinkler.

Additional sprinklers should be installed under fixed obstructions that are more than 4 feet in width (e.g., ducts, overhead doors).System DrainsAll sprinkler systems must be installed so the system may be drained if necessary. If repairs or alterations are required, a main drain valve will allow the system to be emptied. Wet pipe systems may be installed level, while dry pipe and preaction systems must be pitched for drainage. The required pitch is ½ inch per 10 feet for branch lines and ¼ inch per 10 feet for mains. Mains must be pitched at least ½ inch per 10 feet in refrigerated areas.

The required drain pipe size as a function of the riser size is shown in Table 9-4.Hanging and Restraint RequirementsIn general, all components of hanger assemblies that directly attach to the pipe or the building structure must be listed. NFPA 13 does allow a licensed Professional Engineer to certify other hangers if they meet these requirements:

• They can support five times the weight of the water-filled pipe plus 250 pounds at each point of piping support.• These points of support shall be adequate to support the system.

Table 9-3 Spacing for Standard Pendent and Upright Sprinklers

Construction Type System Type Protection Area, sf

Maximum Spacing, ft

Light Hazard

Noncombustible Pipe schedule 200 15Combustible unobstructed, exposed members 3 feet or more on center Pipe schedule 200 15

Noncombustible Hydraulically calculated 225 15Combustible unobstructed, exposed members 3 feet or more on center Hydraulically calculated 225 15

Combustible obstructed, exposed members 3 feet or more on center All 168 15

Combustible obstructed or unobstructed, exposed members less than 3 feet on center All 130 15

Ordinary Hazard

All All 130 15Extra Hazard

All Pipe schedule 90 12

AllHydraulically calculated

with density more than or equal to 0.25

100 12

All Hydraulically calculated with density less than 0.25 130 15

Table 9-4 Drain Sizes for Sprinkler Systems

Riser Pipe, in. Drain Pipe, in.

2 and smaller ¾ or larger2½ to 3½ 1¼ or larger

4 and larger 2



• The spacing between hangers does not exceed that allowed by NFPA 13.• All hanger components are ferrous.• Detailed calculations shall be submitted showing the stresses and safety factors allowed.Sprinkler piping and hangers should not be used to support non-system components.

Hanger rods shall be sized as shown in Table 9-5, and the maximum distance between hangers is shown in Table 9-6.

Except when sprinklers are less than 6 feet apart, a hanger is required on each section of pipe. Sprigs 14 feet or longer need to be restrained against lateral movement. Where sprinkler systems are subject to damage by earthquakes, bracing, restraint, and the use of flexible joints or clearances must be provided.

DESIGN APPROACHESPipe Schedule SystemsWhereas all systems were once designed on a pipe schedule basis, NFPA 13 no longer allows pipe schedules to be used except for modifications or extensions to existing systems or for new systems less than 5,000 square feet. To determine the water supply requirements for a pipe schedule, consult NFPA 13, which gives flow rates and operational durations for light and ordinary hazards. Hydraulically Calculated SystemsThree methods to determine the required water supply using hydraulic calculations follow:

• The design/area method uses design/area curves (see Figure 9-8). For example, a light hazard system can be designed to provide a density of 0.1 gpm over a remote area of 1,500 square feet. Any point along the curve can be selected. Where quick-response sprin-klers are used, the area of sprinkler operation can be reduced by up to 40 percent, depend-ing on the elevation of the ceiling.

• The room design method can be used when all rooms are enclosed with walls having a fire-resistive rating equal to the required water supply duration. This method allows the water supply requirement to be based on the sprinklers in the room that creates the greatest demand. Where a room communicates through an unprotected opening with other rooms, up to two additional sprinklers must be included for each additional room.

• Special design areas: Where a building service chute (trash or linen) is protected with sprinklers, the three most remote sprinklers shall be calculated with a minimum discharge of 15 gpm each. In spaces where residential sprinklers can be used within the scope of NFPA 13, the design area shall include the four adjacent sprinklers that produce the greatest hydraulic demand.

DESIGN AND CONSTRUCTION DOCUMENTSWhen developing a sprinkler system design, code requires certain data to be included on the working design drawings. NFPA 13 lists all of the information required, which includes the following:

• Name, location, and address of the property in which the system will be installed• Owner and occupant• Point of compass (north direction)• Type of construction• Distance from hydrant• Special hazard requirements, etc.

Table 9-5 Hanger Rod Sizing

Pipe Size, in. Rod Diameter, in.

Up to and including 4 3/8

5 to 8 ½10 to 12 5/8

Table 9-6 Maximum Distance Between Hangers, ft

Type of PipePipe Size, in.

1 1¼ 1½ 2 2½ 3 4 6 8

Steel (except threaded lightwall)

12 12 15 15 15 15 15 15 15

Threaded lightwall 12 12 12 12 NA NA NA NA NA

Copper tube 8 10 10 12 12 12 15 15 15CPVC 6 6½ 7 8 9 10 NA NA NA

Figure 9-8 Design Area Curve Example



SYSTEM ACCEPTANCE Hydrostatic TestsWhen the sprinkler system’s operating pressure is 150 psi or less, the test pressure must be 200 psi, and the length of the test must be two hours. For any other operating pressure, the test must be the maximum working pressure plus 50 psi. If the test takes place during the winter, air may be temporarily substituted for water.Pneumatic TestsIn addition to hydrostatic tests, dry pipe and double-interlocked preaction systems require an air pressure leakage test. These systems must be tested at 40 psi for a 24-hour period and must not lose more than 1.5 psi during this period.FlushingAfter installation, underground mains, lead-in connections, and risers must be flushed. This operation is very important, because factory-supplied pipes may contain dust, rust, etc., in addition to impurities and debris collected during installation. If not eliminated, these foreign materials may block a sprinkler’s orifice and render it inoperable. The flushing rates prescribed by NFPA 13 for underground mains are shown in Table 9-7.Operational TestsAll water flow devices should be tested. NFPA 13 allows up to five minutes after flow begins before an audible alarm sounds on the premises.

Dry pipe systems must have a full-flow trip test. The test should be started by opening the inspector’s test connection and measuring the time required to trip the valve and the time for water to discharge from the inspector’s test connection.

Deluge and preaction systems should be trip-tested through both manual and automatic means.All control valves should be operated under system pressure to ensure proper operation.A main drain test should be conducted and recorded for comparison during future tests.Each pressure-reducing valve must be tested at both the maximum and normal inlet pressures.

Table 9-7 Underground Main Flushing Flow Rates

Pipe Size, in. Flow Rate, gpm

4 3906 8808 1,56010 2,440

12 3,520



1. Which of the following is a type of commercially available sprinkler?

a. early suppression, fast responseb. pendentc. quick responsed. all of the above

2. A bakery is an example of which occupancy classification?a. Light Hazardb. Ordinary Hazard Group 1c. Ordinary Hazard Group 2d. Extra Hazard Group 1

3. A _______ employs automatic sprinklers attached to a piping network containing water under pressure at all times.

a. dry pipe systemb. wet pipe systemc. preaction systemd. antifreeze system

4. The maximum floor area that may be protected by sprinklers supplied on each system riser on any one floor for an ordinary hazard occupancy is _______.

a. 25,000 square feetb. 40,000 square feetc. 42,000 square feetd. 52,000 square feet

5. The type of sprinkler piping selected should be based on which of the following?

a. maximum system pressureb. ambient conditionsc. possible exposure of the pipe to fire conditionsd. all of the above

6. What color glass sprinkler bulb indicates an extra high temperature classification?

a. greenb. bluec. purpled. black

7. _______ are used in very high-hazard areas where rapid application of large volumes of water is required to quickly gain control of a fire.

a. deluge systemsb. dry pipe systemsc. preaction systemsd. none of the above

8. What is the flushing rate prescribed by NFPA 13 for an 8-inch underground main?

a. 390 gpmb. 880 gpmc. 1,560 gpmd. 2,440 gpm

9. Extended coverage sprinklers cover more than _______ per head or greater distances than standard sprinklers.

a. 100 square feetb. 125 square feetc. 200 square feetd. 225 square feet

10. Sprinkler system components are typically designed for a minimum pressure of _______.

a. 175 psib. 200 psic. 225 psid. 275 psi

11. What is the maximum distance between hangers for 2½-inch copper tube?

a. 15 feetb. 12 feetc. 10 feetd. 9 feet

12. A _______ system is often used where valuables are stored and accidental water discharge may cause damage.

a. dry pipeb. antifreezec. preactiond. deluge

ASPE Read, Learn, Earn Continuing EducationYou may submit your answers to the following questions online at aspe.org/readlearnearn. If you score 90 percent or higher on the test, you will be notified that you have earned 0.1 CEU, which can be applied toward CPD renewal or numerous regulatory-agency CE programs. (Please note that it is your responsibility to determine the acceptance policy of a particular agency.) CEU information will be kept on file at the ASPE office for three years.

Notice for North Carolina Professional Engineers: State regulations for registered PEs in North Carolina now require you to complete ASPE’s online CEU validation form to be eligible for continuing education credits. After successfully completing this quiz, just visit ASPE’s CEU Validation Center at aspe.org/CEUValidationCenter.

Expiration date: Continuing education credit will be given for this examination through December 31, 2017.

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