Pressure gauges shall be installed above and below each alarm check valve or system riser check valve where such devices are present.
Where auxiliary air reservoirs are installed to absorb pressure increases, a relief valve shall not be required.
A wet pipe system shall be permitted to supply an auxiliary dry pipe, preaction, or deluge system, provided the water supply is adequate.
Approved pressure gauges in accordance with 8.17.3 shall be connected as follows:
- On the water side and air side of the dry pipe valve
- At the air pump supplying the air receiver where one is provided
- At the air receiver where one is provided
- In each independent pipe from air supply to dry pipe system
- At quick-opening devices
The following sprinkler orientations and arrangements shall be permitted for dry pipe systems:
- Upright sprinklers
- *Listed dry sprinklers
- Pendent sprinklers and sidewall sprinklers installed on return bends, where the sprinklers, return bend, and branch line piping are in an area maintained at or above 40°F (4°C)
- Horizontal sidewall sprinklers installed so that water is not trapped
- Pendent sprinklers and sidewall sprinklers, where the sprinklers and branch line piping are in an area maintained at or above 40°F (4°C), the water supply is potable, and the piping for the dry pipe system is copper or CPVC specifically listed for dry pipe applications
For dry pipe systems protecting dwelling unit portions of any occupancy, system size shall be such that initial water is discharged from the system test connection in not more than 15 seconds, starting at the normal air pressure on the system and at the time of fully opened inspection test connection.
Dry pipe systems protecting dwelling unit portions of any occupancy shall not be permitted to use the options outlined in 7.2.3.2, 7.2.3.3, or 7.2.3.4.
A system size of not more than 500 gal (1893 L) shall be permitted without a quick-opening device and shall not be required to meet any specific water delivery requirement to the inspection test connection.
A system size of not more than 750 gal (2839 L) shall be permitted with a quick-opening device and shall not be required to meet any specific water delivery requirement to the inspection test connection.
System size shall be based on dry pipe systems being calculated for water delivery in accordance with 7.2.3.6.
Calculations for dry pipe system water delivery shall be based on the hazard shown in Table 7.2.3.6.1.
Table 7.2.3.6.1 Dry Pipe System Water Delivery
| Hazard | Number of Most Remote Sprinklers Initially Open | Maximum Time of Water Delivery (seconds) |
|---|---|---|
| Light | 1 | 60 |
| Ordinary I | 2 | 50 |
| Ordinary II | 2 | 50 |
| Extra I | 4 | 45 |
| Extra II | 4 | 45 |
| High piled | 4 | 40 |
The calculation program and method shall be listed by a nationally recognized testing laboratory.
For dry pipe systems protecting dwelling unit portions of any occupancy, the sprinklers in the dwelling unit shall have a maximum water delivery time of 15 seconds to the single most remote sprinkler.
Residential sprinklers shall be listed for dry pipe applications.
System size shall be such that initial water discharge from the system trip test connection or manifold outlets is not more than the maximum time of water delivery specified in Table 7.2.3.6.1, starting at normal air pressure on the system and at the time of fully opened test connection.
When flow is from four sprinklers, the test manifold shall be arranged to simulate two sprinklers on each of two sprinkler branch lines.
When flow is from three sprinklers, the test manifold shall be arranged to simulate two sprinklers on the most remote branch line and one sprinkler on the next adjacent branch line.
When flow is from two sprinklers, the test manifold shall be arranged to simulate two sprinklers on the most remote branch line.
Unless installed in a heated enclosure, check valves shall not be used to subdivide the dry pipe systems.
When check valves are used to subdivide dry pipe systems in accordance with 7.2.3.9, a hole 1/8 in. (3 mm) in diameter shall be drilled in the clapper of each check valve to permit equalization of air pressure among the various parts of the system.
Where auxiliary drains are not provided for each subdivided section, an approved indicating drain valve supervised in the closed position in accordance with 8.16.1.1.2, connected to a bypass around each check valve, shall be provided as a means for draining the system.
Gridded dry pipe systems shall not be installed.
To protect the restriction orifice and other operating parts of the quick-opening device against submergence, the connection to the riser shall be above the point at which water (priming water and back drainage) is expected when the dry pipe valve and quick-opening device are set, except where design features of the particular quick-opening device make these requirements unnecessary.
A check valve shall be installed between the quickopening device and the intermediate chamber of the dry pipe valve, where the quick-opening device requires protection against submergence after system operation.
If the quick-opening device requires pressure feedback from the intermediate chamber, a valve type that will clearly indicate whether it is opened or closed shall be permitted in place of that check valve.
Unless the requirements of 7.2.4.8.2 are met, a listed antiflooding device shall be installed in the connection between the dry pipe sprinkler riser and the quick-opening device.
The dry pipe valve and supply pipe shall be protected against freezing and mechanical injury.
The source of heat shall be of a permanently installed type.
The supply for the sprinkler in the dry pipe valve enclosure shall be either from the dry side of the system or from a wet pipe sprinkler system that protects the area where the dry pipe valve is located.
An automatic high water level signaling device or an automatic drain shall be permitted.
The compressed air supply shall be from a source available at all times.
The air supply shall have a capacity capable of restoring normal air pressure in the system within 30 minutes.
A check valve shall be installed in the air filling connection, and a listed or approved shutoff valve of either the renewable disc or ball valve type shall be installed on the supply side of this check valve and shall remain closed unless filling the system.
Unless the requirements of 7.2.6.6.2 are met, where the air supply to a dry pipe system is maintained automatically, the air supply shall be from a dependable plant system or an air compressor with an air receiver, and shall utilize an air maintenance device specifically listed for such service and capable of controlling the required air pressure on, and maximum airflow to, the dry pipe system.
Where the air compressor supplying the dry pipe system has a capacity less than 5.5 ft3/min (156 L/min) at 10 psi (0.7 bar), an air receiver or air maintenance device shall not be required.
The automatic air supply to more than one dry pipe system shall be connected to enable individual maintenance of air pressure in each system.
A check valve or other positive backflow prevention device shall be installed in the air supply to each system to prevent airflow or waterflow from one system to another.
Where nitrogen or other approved gas is used, the supply shall be from a reliable source.
A low pressure alarm shall be provided on gas storage containers to notify the need for refilling.
All components of pneumatic, hydraulic, or electrical systems shall be compatible.
The automatic water control valve shall be provided with hydraulic, pneumatic, or mechanical manual means for operation that is independent of detection devices and of the sprinklers.
A supply of spare fusible elements for heat-responsive devices, not less than two of each temperature rating, shall be maintained on the premises for replacement purposes.
Spacing of releasing devices, including automatic sprinklers used as releasing devices, shall be in accordance with their listing and manufacturer's specifications.
The release system shall serve all areas that the preaction system protects.
Where thermal activation is utilized, the activation temperature of the release system shall be lower than the activation temperature of the sprinkler.
Testing apparatus capable of producing the heat or impulse necessary to operate any normal detection device shall be furnished to the owner of the property with each installation.
Where explosive vapors or materials are present, hot water, steam, or other methods of testing not involving an ignition source shall be used.
A separate additional indicating control valve, supervised in accordance with 8.16.1.1.2, shall be permitted to be installed in the riser assembly above a preaction or deluge valve to permit full function trip testing as required by NFPA 25, without flooding the system.
System water control valves and supply pipes shall be protected against freezing and mechanical injury.
Valve rooms shall be lighted and heated.
The source of heat shall be of a permanently installed type.
Preaction systems shall be one of the following types:
- A single interlock system, which admits water to sprinkler piping upon operation of detection devices
- A non-interlock system, which admits water to sprinkler piping upon operation of detection devices or automatic sprinklers
- A double interlock system, which admits water to sprinkler piping upon operation of both detection devices and automatic sprinklers
Not more than 1000 automatic sprinklers shall be controlled by any one preaction valve.
The system size controlled by a double interlock preaction valve shall be determined by either 7.3.2.3.1.1, 7.3.2.3.1.2, 7.3.2.3.1.3, and 7.3.2.3.1.4.
A system size for double interlock preaction systems of not more than 500 gal (1893 L) shall be permitted and shall not be required to meet any specific water delivery requirement to the trip test connection.
The system size for double interlock preaction systems shall be based on calculating water delivery in accordance with 7.2.3.6, anticipating that the detection system activation and sprinkler operation will be simultaneous.
The system size for double interlock preaction systems shall be designed to deliver water to the system trip test connection or manifold outlets in not more than the maximum time of water delivery specified in Table 7.2.3.6.1, starting at the normal air pressure on the system, with the detection system activated and the inspection trip test connection or manifold opened simultaneously.
A listed quick-opening device shall be permitted to be used to help meet the requirements of 7.3.2.3.1.2, 7.3.2.3.1.3, and 7.3.2.3.1.4.
Sprinkler piping and fire detection devices shall be automatically supervised where more than 20 sprinklers are on the system.
The following sprinkler orientations and arrangements shall be permitted for preaction systems:
- Upright sprinklers
- *Listed dry sprinklers
- Pendent sprinklers and sidewall sprinklers installed on return bends, where the sprinklers, return bend, and branch line piping are in an area maintained at or above 40°F (4°C)
- Horizontal sidewall sprinklers, installed so that water is not trapped
- Pendent sprinklers and sidewall sprinklers, where the sprinklers and branch line piping are in an area maintained at or above 40°F (4°C), the water supply is potable, and the piping for the preaction system is copper or CPVC specifically listed for dry pipe applications
Preaction systems of the type described in 7.3.2.1(3) and all preaction systems protecting storage occupancies, excluding miscellaneous storage, shall not be gridded.
In addition to the requirements of Section 7.4, design and installation requirements for piers, terminals, and wharves shall be in accordance with Section 22.22.
Combined automatic dry pipe and preaction systems shall be so constructed that failure of the detection system shall not prevent the system from functioning as a conventional automatic dry pipe system.
Combined automatic dry pipe and preaction systems shall be so constructed that failure of the dry pipe system of automatic sprinklers shall not prevent the detection system from properly functioning as an automatic fire alarm system.
Provisions shall be made for the manual operation of the detection system at locations requiring not more than 200 ft (61 m) of travel.
The following types of sprinklers and arrangements shall be permitted for combined dry pipe and preaction systems:
- Upright sprinklers
- *Listed dry sprinklers
- Pendent sprinklers and sidewall sprinklers installed on return bends, where both the sprinklers and the return bends are located in a heated area
- Horizontal sidewall sprinklers, installed so that water is not trapped
Where the system consists of more than 600 sprinklers or has more than 275 sprinklers in any fire area, the entire system shall be controlled through two 6 in. (150 mm) dry pipe valves connected in parallel and shall feed into a common feed main.
Each dry pipe valve shall be provided with a listed tripping device actuated by the detection system.
The 1 in. (25 mm) cross-connection pipe shall be equipped with an indicating valve so that either dry pipe valve can be shut off and worked on while the other remains in service.
The check valves between the dry pipe valves and the common feed main shall be equipped with 1/2 in. (15 mm) bypasses so that a loss of air from leakage in the trimmings of a dry pipe valve will not cause the valve to trip until the pressure in the feed main is reduced to the tripping point.
An indicating valve shall be installed in each of these bypasses so that either dry pipe valve can be completely isolated from the main riser or feed main and from the other dry pipe valve.
Where more than 275 sprinklers are required in a single fire area, the system shall be divided into sections of 275 sprinklers or fewer by means of check valves.
Where the system is installed in more than one fire area or story, not more than 600 sprinklers shall be supplied through any one check valve.
Each section shall have a 114 in. (32 mm) drain on the system side of each check valve supplemented by a dry pipe system auxiliary drain.
The sprinkler system shall be so constructed and the number of sprinklers controlled shall be so limited that water shall reach the farthest sprinkler within a period of time not exceeding 1 minute for each 400 ft (122 m) of common feed main from the time the heat-responsive system operates.
The maximum time permitted shall not exceed 3 minutes.
The end section shall have a system test connection as required for dry pipe systems.
All multi-cycle systems shall be specifically tested and listed as systems.
All multi-cycle systems shall be installed in compliance with the manufacturer's installation instructions.
| Section 7.6 was revised by a tentative interim amendment (TIA). See page 1. |
The use of antifreeze solutions shall be in conformity with state and local health regulations.
Where pendent sprinklers are utilized, the water shall be drained from the entire system after hydrostatic testing with water.
Where antifreeze systems are remote from the system riser, a placard shall be mounted on the system riser that indicates the number and location of all remote antifreeze systems supplied by that riser.
Except as permitted in 7.6.2.2, antifreeze solutions shall be listed for use in sprinkler systems.
Premixed antifreeze solutions of propylene glycol shall be permitted to be used with ESFR sprinklers where the ESFR sprinklers are listed for such use in a specific application.
Where the connection between the antifreeze system and the wet pipe system does not incorporate a backflow prevention device, and the conditions of 7.6.3.5 are not met, piping and valves shall be installed as illustrated in Figure 7.6.3.1. 
Notes:
- Check valves are permitted to be omitted where sprinklers are below the level of valve A.
- The 1/32 in. (0.8 mm) hole in the check valve clapper is needed to allow for expansion of the solution during a temperature rise, thus preventing damage to sprinklers.
FIGURE 7.6.3.1 Arrangement of Supply Piping and Valves.
Where the connection between the antifreeze system and the wet pipe system incorporates a backflow prevention device, and the conditions of 7.6.3.5 are not met, a listed expansion chamber shall be provided to compensate for thermal expansion of the antifreeze solution as illustrated in Figure 7.6.3.3. 
FIGURE 7.6.3.3 Arrangement of Supply Piping with Backflow Device.
When determining the size of the expansion chamber, the precharge air temperature and precharge air pressure shall be included.
The requirements of paragraphs 7.6.3.1, 7.6.3.2, and 7.6.3.3 shall not apply where the following three conditions are met:
- The antifreeze system is provided with an automatic pressure pump or other device or apparatus to automatically maintain a higher pressure on the system side than on the supply side of the water supply check valve separating the antifreeze system from the water supply.
- Provision is made to automatically release solution to prevent overpressurization due to thermal expansion of the solution.
- Provision is made to automatically supply premixed solution as needed to restore system pressure due to thermal contraction.
For systems with a capacity larger than 150 gal (567.8 L), an additional test connection shall be provided for every 100 gal (378.5 L). 
Notes:
- Check valve can be omitted where sprinklers are below the level of valve A.
- The 1/32 in. (0.8 mm) hole in the check valve clapper is needed to allow for expansion of the solution during a temperature rise, thus preventing damage to sprinklers.
FIGURE 7.6.3.4 Arrangement of Supply Piping with Relief Valve and Backflow Device.
A circulating closed-loop system is primarily a sprinkler system and shall comply with all provisions of this standard such as those for control valves, area limitations of a system, alarms, fire department connections, sprinkler spacing, and so forth, except as modified by Section 7.7.
Unless the requirements of 7.7.1.1.4 are met, a dielectric fitting shall be installed in the junction where dissimilar piping materials are joined (e.g., copper to steel).
Dielectric fittings shall not be required in the junction where sprinklers are connected to piping.
Other auxiliary devices shall not be required to be listed for sprinkler service; however, these devices, such as pumps, circulating pumps, heat exchangers, radiators, and luminaires, shall be pressure rated at 175 psi or 300 psi (12.1 bar or 20.7 bar) (rupture pressure of five times rated water system working pressure) to match the required rating of sprinkler system components.
Auxiliary devices shall incorporate materials of construction and be so constructed that they will maintain their physical integrity under fire conditions to avoid impairment to the fire protection system.
Auxiliary devices, where hung from the building structure, shall be supported independently from the sprinkler portion of the system, following recognized engineering practices.
Piping systems for attached heating and cooling equipment shall have auxiliary pumps or an arrangement made to return water to the piping system in order to ensure the following:
- Water for sprinklers shall not be required to pass through heating or cooling equipment.
- At least one direct path shall exist for waterflow from the sprinkler water supply to every sprinkler.
- Pipe sizing in the direct path shall be in accordance with the design requirements of this standard.
- No portions of the sprinkler piping shall have less than the sprinkler system design pressure, regardless of the mode of operation of the attached heating or cooling equipment.
- There shall be no loss or outflow of water from the system due to or resulting from the operation of heating or cooling equipment.
- Shutoff valves and a means of drainage shall be provided on piping to heating or cooling equipment at all points of connection to sprinkler piping and shall be installed in such a manner as to make possible repair or removal of any auxiliary component without impairing the serviceability and response to the sprinkler system.
- All auxiliary components, including the strainer, shall be installed on the auxiliary equipment side of the shutoff valves.
In no case shall maximum water temperature flowing through the sprinkler portion of the system exceed 120°F (49°C).
Protective control devices listed for this purpose shall be installed to shut down heating or cooling systems when the temperature of water flowing through the sprinkler portion of the system exceeds 120°F (49°C).
Where the water temperature exceeds 100°F (37.8°C), intermediate or higher temperature-rated sprinklers shall be used.
Precautions shall be taken to ensure that temperatures below 40°F (4°C) are not permitted.
Automatic sprinklers shall not be obstructed by auxiliary devices, piping, insulation, and so forth, from detecting fire or from proper distribution of water.
Materials added to water shall not adversely affect the fire-fighting properties of the water and shall be in conformity with any state or local health regulations.
Due care and caution shall be given to the use of additives that can remove or suspend scale from older piping systems.
Where additives are necessary for proper system operation, due care shall be taken to ensure that additives are replenished after alarm testing or whenever water is removed from the system.
The supply of water from sprinkler piping through auxiliary devices, circulatory piping, and pumps shall not under any condition or operation, transient or static, cause false sprinkler waterflow signals.
Exposure protection sprinkler systems shall be permitted on buildings and structures regardless of whether the building's interior is protected by a sprinkler system.
Where exposure protection systems are required, they shall be installed to provide protection of windows and other openings within masonry walls, complete protection of walls, protection of roofs, or any combination thereof.
Unless the requirements of 7.8.2.2 are met, sprinklers installed for protection against exposure fires shall be supplied from a standard water supply as outlined in Chapter 24.
Where approved, other supplies, such as manual valves or pumps or fire department connections, shall be permitted to supply water to sprinklers for exposure protection.
Where fire department connections are used for water supply, they shall be so located that they will not be affected by the exposing fire.
Each system of outside sprinklers shall have an independent control valve.
Manually controlled open sprinklers shall be used only where constant supervision is present.
Sprinklers shall be of the open or automatic type.
| Paragraph 7.8.3.4 was revised by a tentative interim amendment (TIA). See page 1. |
Automatic sprinklers in areas subject to freezing shall be on dry pipe systems conforming to Section 7.2, on antifreeze systems conforming to Section 7.6, or be dry sprinklers of an adequate length connected to wet pipe systems located in heated areas.
Automatic systems of open sprinklers shall be controlled by the operation of fire detection devices designed for the specific application.
Each system of outside sprinklers shall have a separate drain valve installed on the system side of each control valve, except where an open sprinkler, top-fed system is arranged to facilitate drainage.
Where sprinklers are installed on two adjacent sides of a building, protecting against two separate and distinct exposures, with separate control valves for each side, the end lines shall be connected with check valves located so that one sprinkler around the corner will operate.
The intermediate pipe between the two check valves shall be arranged to drain.
As an alternate solution, an additional sprinkler shall be installed on each system located around the corner from the system involved.
Where one exposure affects two sides of the protected structure, the system shall not be subdivided between the two sides but rather shall be arranged to operate as a single system.
Pipe and fittings installed on the exterior of the building or structure shall be corrosion resistant.
A listed strainer shall be provided in the riser or feed main that supplies sprinklers having nominal K-factors smaller than K-2.8 (40).
A listed pressure gauge conforming with 8.17.3 shall be installed immediately below the control valve of each system.
A single line of sprinklers is permitted to protect a maximum of two stories of wall area or two levels of vertically aligned windows where architectural features are sufficiently flush to allow rundown.
Where window sills or similar features result in recesses or projections exceeding 1 in. (25.4 mm) in depth, separate sprinklers shall be provided for each window on each level, regardless of whether protection is being provided for windows or complete walls.
For wall protection systems, sprinklers shall be located 6 in. to 12 in. (152 mm to 305 mm) from the wall surface and within 6 in. (152 mm) of the top of the wall, with maximum spacing of 8 ft (2.44 m) or as indicated in the sprinkler listing for exposure protection use.
For protection of window and similar openings, listed window sprinklers shall be positioned within 2 in. (50.8 mm) of the top of the window sash in accordance with Table 7.8.8.4.
Table 7.8.8.4 Position of Window Sprinklers
| Width of Window (ft) | Nominal K-Factor | Nominal Distance from Window (in.) | |
|---|---|---|---|
| U.S. | Metric | ||
| Up to 3 | 2.8 | 40 | 7 |
| >3 to 4 | 2.8 | 40 | 8 |
| >4 to 5 | 2.8 | 40 | 9 |
| 5.6 | 80 | 12 | |
| >5 to 7 | 11.2 | 160 | 12 |
| Two 2.8 | 40 | 7 | |
| >7 to 9.5 | 14.0 | 200 | 12 |
| Two 2.8 | 40 | 9 | |
| >9.5 to 12 | Two 5.6 | 80 | 12 |
| For SI units, 1 ft = 0.3048 m. | |||
Where exposure protection sprinkler systems are installed, listed cornice sprinklers shall be used to protect combustible cornices exceeding 12 in. (305 mm) in depth.
Open spray sprinklers (upright, pendent, or sidewall) shall be permitted for application in roof protection when installed in accordance with ordinary hazard Group 1 protection areas and discharge criteria, with deflectors aligned parallel to the slope and positioned a minimum 18 in. (457 mm) above the roof surface.
Upright sprinklers positioned as ridge pole sprinklers shall be permitted with their deflectors horizontal and minimum 6 in. (152 mm) above the ridge, with their maximum spacing and protection areas determined in the plan view rather than along the slope.
Where temperatures are maintained above 32°F (0°C) in refrigerated spaces, the requirements in this section shall not apply.
Where sprinkler pipe passes through a wall or floor into the refrigerated space, a section of pipe arranged for removal shall be provided immediately inside the space.
Piping in refrigerated spaces shall be installed with pitch as outlined in 8.16.2.3.3.
Air or nitrogen supply for systems shall be one of the following:
- Air from the room of lowest temperature to reduce the moisture content
- Air compressor/dryer package listed for the application utilizing ambient air
- Compressed nitrogen gas from cylinders used in lieu of compressed air
An indicating-type control valve for operational testing of the system shall be provided on each sprinkler riser outside of the refrigerated space.
Unless the requirements of 7.9.2.6.2 are met, a check valve with a 3/32 in. (2.4 mm) diameter hole in the clapper shall be installed in the system riser below the test valve required in 7.9.2.5.
Check valves shall not be required where dry pipe or preaction valves are used and designed to completely drain all water above the seat and that are listed for installation without priming water remaining and where priming water is not used in the system riser.
The air or nitrogen supply piping entering the freezer area shall be as stated in 7.9.2.7.1.1 and 7.9.2.7.1.2.
The supply piping shall be equipped with two easily removable supply lines at least 6 ft (1.9 m) long and at least 1 in. (25 mm) in diameter as shown in Figure 7.9.2.7.1.1(a) or Figure 7.9.2.7.1.1(b).
Notes:
- Check valve with 3/32 in. (2.4 mm) hole in clapper not required if prime water not used.
- Supply air to be connected to top or side of system pipe.
- Each removable air line to be a minimum of 1 in. (25 mm) diameter and a minimum of 6 ft (1.8 m) long.
FIGURE 7.9.2.7.1.1(a) Refrigerator Area Sprinkler System Used to Minimize the Chances of Developing Ice Plugs.
Notes:
- Check valve with 3/32 in. (2.4 mm) hole in clapper not required if prime water not used.
- Each removable air line is to be installed a minimum of 1 in. (25 mm) in diameter and a minimum of 6 ft (1.8 m) long.
FIGURE 7.9.2.7.1.1(b) Preaction System Arrangement.
The supply piping shall be equipped with a single easily removable supply line at least 6 ft (1.9 m) long and at least 1 in. (25 mm) in diameter.
Each supply line shall be equipped with control valves located in the warm area.
Only one air supply line shall be open to supply the system air at any one time.
The release system shall be designed to operate prior to sprinkler operation, unless detectors meet the requirements of 7.9.2.8.1.2.
Where the system is a double interlock preaction system or single interlock preaction antifreeze system, detection devices shall be permitted to be any type specifically approved for use in a refrigerated area if installed in accordance with their listing requirements and NFPA 72.
Under smooth ceilings, detectors shall be spaced not exceeding their listed spacing.
For other than smooth ceilings, detectors shall not exceed one-half of the listed linear detector spacing or full allowable sprinkler spacing, whichever is greater.
Unless conditions in 7.9.2.8.4 are met, one level of detectors shall be installed for each level of sprinklers.
Detectors shall be installed vertically within one storage level of the rack sprinklers and as follows:
- Detectors shall be located in the transverse flue in single-row racks and in the longitudinal flue in double-row racks.
- For multiple-row racks, detectors shall be located in either longitudinal or transverse flue space and shall be within 5 ft (1.5 m) horizontally of each sprinkler.
- Separate detection systems shall be installed for ceiling sprinkler systems and in-rack sprinkler systems.
- Where system is double interlock preaction type, ceiling detection system shall operate solenoid valves on both ceiling and in-rack preaction systems.
Ceiling detection only shall be permitted where all of the following conditions are met: 
- Maximum storage height is 35 ft (10.7 m).
- Maximum ceiling height is 40 ft (12.2 m).
- Maximum hazard of storage is Class III.
- No solid shelves are present.
- One preaction valve is used for both ceiling and in-rack sprinklers protecting the same area, with separate indicating control valves and check valves provided downstream as shown in Figure 7.9.2.8.4.
- Detectors at the ceiling are spaced at a maximum of one-half the listed detector spacing but not less than the sprinkler spacing.
FIGURE 7.9.2.8.4 Valve Arrangement.
Upcodes Diagrams
In cooking areas protected by automatic sprinklers, additional sprinklers or automatic spray nozzles shall be provided to protect commercial-type cooking equipment and ventilation systems that are designed to carry away grease-laden vapors unless otherwise protected.
Sprinklers or automatic spray nozzles in ducts, duct collars, and plenum chambers shall not be required where all cooking equipment is served by listed grease extractors.
Hoods containing automatic fire-extinguishing systems are protected areas; therefore, these hoods are not considered obstructions to overhead sprinkler systems and shall not require floor coverage underneath.
Cooking equipment below hoods that contain automatic fire-extinguishing equipment is protected and shall not require protection from the overhead sprinkler system.
Sprinklers or automatic spray nozzles shall not be required in a vertical riser located outside of a building, provided the riser does not expose combustible material or provided the interior of the building and the horizontal distance between the hood outlet and the vertical riser is at least 25 ft (7.6 m).
Unless the requirements of 7.10.3.4 are met, horizontal exhaust ducts shall have sprinklers or automatic spray nozzle devices located on 10 ft (3 m) centers beginning no more than 5 ft (1.5 m) from the duct entrance.
Where ducts do not exceed 75 ft (22.86 m) in length and the entire exhaust duct is protected in accordance with NFPA 96, sprinkler(s) or automatic spray nozzle(s) shall not be required.
Each hood exhaust duct collar shall have one sprinkler or automatic spray nozzle located 1 in. minimum to 12 in. maximum (25 mm minimum to 305 mm maximum) above the point of duct collar connection in the hood plenum.
Hoods that have listed fire dampers located in the duct collar shall be protected with a sprinkler or automatic spray nozzle located on the discharge side of the damper and shall be so positioned as not to interfere with damper operation.
Hood exhaust plenum chambers shall have one sprinkler or automatic spray nozzle centered in each chamber not exceeding 10 ft (3 m) in length.
Where the exposed temperature is expected to be 300°F (149°C) or less, sprinklers or automatic spray nozzles being used in duct, duct collar, and plenum areas shall be of the extra high-temperature classification [325°F to 375°F (163°C to 191°C)].
When use of a temperature-measuring device indicates temperatures above 300°F (149°C), a sprinkler or automatic spray nozzle of higher classification shall be used.
Access shall be provided to all sprinklers or automatic spray nozzles for examination and replacement.
Cooking equipment (such as deep fat fryers, ranges, griddles, and broilers) that is considered to be a source of ignition shall be protected in accordance with the provisions of 7.10.1.
Asprinkler or automatic spray nozzle used for protection of deep fat fryers shall be listed for that application.
The position, arrangement, location, and water supply for each sprinkler or automatic spray nozzle shall be in accordance with its listing.
The operation of any cooking equipment sprinkler or automatic spray nozzle shall automatically shut off all sources of fuel and heat to all equipment requiring protection.
Any gas appliance not requiring protection but located under ventilating equipment shall also be shut off.
All shutdown devices shall be of the type that requires manual resetting prior to fuel or power being restored.
A listed indicating valve shall be installed in the water supply line to the sprinklers and spray nozzles protecting the cooking and ventilating system.
A listed line strainer shall be installed in the main water supply preceding sprinklers or automatic spray nozzles having nominal K-factors smaller than K-2.8 (40).
Additives to the water supply intended for control of microbiological or other corrosion shall be listed for use within fire sprinkler systems.
Internal pipe coatings, excluding galvanizing, intended for control of microbiological or other corrosion shall be listed for use within fire sprinkler systems.