Reprinted with permission from NFPA journal (Vol. 95  No. 4) copyright.
2000 National Fire Protection Association; and the NFPA Web site copyright.
2002 National Fire Protection Association.

Important Notice: The responses to these Frequently Asked Questions are prepared by NFPA technical staff to assist users in reading and  understanding NFPA codes and standards. The responses, however, are not Formal Interpretations issued pursuant to NFPA Regulations. Any opinions expressed are the personal opinions of the author(s), and do not necessarily represent the official position of the NFPA or its  Technical Committees. In addition, the responses are neither intended, nor should be relied upon, to provide professional consultation or services.

• NFPA 13 Standards for Automatic Sprinklers Installation
• NFPA 13 Standards for Automatic Sprinklers and Storage Facilities

NFPA 13 Standard for Automatic Sprinklers Installation

• Do I need sprinklers in my building?
• Can plastic pipe be used on a sprinkler system complying with  NFPA 13?
• What is the limit for the calculated water velocity in a sprinkler system complying with NFPA 13?
• Do walk-in type freezers, coolers, vaults, and safes require  sprinklers?
• Are sprinklers required in closets?
• Can a supply control valve be installed downstream of the fire  department connection?
• What is the allowable reduction in fire separation ratings in a building where a sprinkler system is installed?
• Are sprinklers required in the upper portion of an architectural ceiling feature?
• Are sprinklers required within furniture?
• Must I design the sprinkler system to protect the same hazard throughout the structure?
• If there are no hose connections in a building sprinklered to NFPA 13, will the water demand need to include a hose stream allowance?
  
  Q. Do I need sprinklers in my building?

NFPA 13 is the NFPA document that specifies the minimum requirements for designing and installing sprinkler systems. It does not specify which buildings require a sprinkler system. The requirement to install a sprinkler system complying with NFPA 13 can usually be found in one of the following sources: building code; federal, state or local regulations; insurer's requirements; accreditation requirements; or owner's request.

Q. Can plastic pipe be used on a sprinkler system complying with  NFPA 13?

Plastic pipe that has been specifically listed for fire protection use is permitted. This pipe must be installed in accordance with its listing limitations, including installation instructions.

Q. What is the limit for the calculated water velocity in a sprinkler system complying with NFPA 13?

NFPA 13 does not specify a maximum limit for the calculated water velocity. 

Q. Do walk-in type, freezers, coolers, vaults, and safes require  sprinklers?

Yes. These areas require sprinklers because they are part of the premises. NFPA 13 requires that sprinklers be installed throughout the premises. There are no exceptions provided which allow for sprinkler omission in these areas.

Q. Are sprinklers required in closets?

Yes. There are limited exceptions for certain small closets in the dwelling units of hotels and motels.

Q. Can a supply control valve be installed downstream of the fire  department connection?

Normally, a control valve is required before and after each check valve in a source of supply. The valves are required so that the check valve can be isolated and serviced. As well, a control valve is normally required in each automatic source of supply. However, these control valves are not necessary, nor allowed, in the fire department connection piping. While the control valves are not allowed in the fire department connection piping itself, control valves can be installed downstream from the fire department connection piping. It would be impractical to require a fire department connection after all control valves in a multi-zone or multi-system arrangement. Furthermore, NFPA13 requires that all valves controlling water supplies be supervised in the open position.

Q. What is the allowable reduction in fire separation ratings in a building where a sprinkler system is installed?

NFPA 13 does not address such reductions. Some building/fire codes will specify an allowable reduction in fire separation ratings for certain buildings where sprinklers are provided in accordance with NFPA 13. You would need to consult with the applicable building/fire code for your particular project to determine if there are any allowable reductions.

Q. Are sprinklers required in the upper portion of an architectural ceiling feature, even when there are no openings to above and the sprinklers at the lower portion do not exceed area of coverage limitations?

This question usually arises with architectural features such as skylights and rooms with multi-level ceilings. The general concern with these types of features is the potential for heat to 'pocket' and the negative impact to the operation of the sprinklers. This could be true even if sprinklers are spaced within their limitations for allowable area of protection. NFPA 13 does not specifically address the sprinkler requirements for these architectural features. However, the applicable sections of Chapter 4 do address the distance below the ceiling that sprinklers must be positioned. The need for sprinklers in the upper portion can be determined based on the distance from the upper level to the position at which the sprinklers would be installed on the lower level. If this distance exceeds the allowable distances specified in Chapter 4, then sprinklers would be required at the upper level. Obstructions specified by Chapter 4 to any of the sprinklers would also need to be examined and accounted for.

Q. Are sprinklers required within furniture?

No. Sprinklers are required within all permanent spaces of the structure, such as closets. Moveable furniture items, such as desks, dressers and wardrobes, do not require sprinklers within them even when they are affixed to the permanent structure of the building.

Q. Must I design the sprinkler system to protect the same hazard throughout the structure?

No. NFPA 13 does not require that the entire structure be protected as a single hazard classification. There are two important things to keep in mind, however, when designing a system with multiple hazard classifications. The first is that you will lock the building
use into the hazard configuration that the sprinkler system is designed for. If the entire space were protected for the highest hazard, however, the building user would not have to worry about the general locations of the different hazards. Additionally, the hydraulic calculation procedure becomes more complex with multiple hazard classifications than where the highest hazard is used throughout.

Q. If there are no hose connections in a building sprinklered to NFPA 13, will the water demand need to include a hose stream allowance?

Yes. An outside hose stream demand would be required.

NFPA 13 Standards for Automatic Sprinklers and Storage Facilities

• In terms of sprinkler protection, what differentiates storage facilities from non-storage facilities?
• How does NFPA 13 classify fire hazards for sprinkler protection?
• Does NFPA address other fire hazards that don't fall into the occupancy hazard or commodity classifications?
• What about sprinkler protection for flammable liquid and aerosol storage?
• What effects does fire hazard have on sprinkler system design and installation?
• What physical characteristics set storage facilities apart form non-storage facilities?
• What is miscellaneous storage?
• How should the sales areas of a mercantile facility by classified?
• What about small storage rooms and closets?
• Are there any conditions under which storage facilities can be protected in accordance with the occupancy hazards?
• What about requirements for small hose?
• Where rack storage is involved, are in-rack sprinklers always necessary?
• Does NFPA 13 offer more than one design option for protecting storage facilities? 

Q. In terms of sprinkler protection, what differentiates storage facilities from non-storage facilities?

A. Overall, the purpose of storage facilities is to stockpile the maximum amount of materials into the smallest possible space while maintaining effective access for material handling. From a fire perspective, this translates into squeezing the maximum amount of combustibles into the smallest possible space while maintaining plenty of air access for efficient combustion. The net result is a prescription for maximized burning of large quantities of materials. 

The type, amount, and arrangement of combustible present relates to the type of fire hazard present. Within the context of NFPA 13, fire hazard links the burning characteristics of a fuel with the ability of a sprinkler system to control or suppress the associated fire. Determination of the fire hazard represents one of the most critical decisions concerning sprinkler system design. Chapter 2 of NFPA 13 provides information on how to classify fire hazards with respect to sprinkler protection.

Q. How does NFPA 13 classify fire hazards for sprinkler protection?

A. NFPA 13 differentiates between fire hazards in storage and non-storage facilities. Fire hazards, for non-storage operations are normally classified according to the occupancy hazard classifications (Section 2-1). NFPA 13 addresses five major occupancies: Light Hazard, Ordinary Hazard Group 1, Ordinary Hazard Group 2, Extra Hazard Group 1, Extra Hazard Group 2.

Fire Hazards in storage facilities are normally classified according to the commodity classifications (Section 2-2). NFPA 13 addresses five basic commodity classifications, including Classes I, II, III, and IV, and plastics. Class I commodities represent the least severe fire hazard, and plastics represent the most severe.

Q. Does NFPA address other fire hazards that don't fall into the occupancy hazard or commodity classifications?

A. NFPA 13 specifically addresses four other storage commodities that make up their own commodity classification. These are rubber tires, baled cotton, rolled paper, and idle pallets.

Certain storage and non-storage operations could also be classified as special hazards (Section 7-10), for example, fire hazards in laboratories using chemicals, and fire hazards associated with storing organic peroxide formulations.

Q. What about sprinkler protection for flammable liquid and aerosol storage?

A. NPFA 13 doesn't provide sprinkler system information about the storage of flammable liquids, combustible liquids, or aerosol products. Instead, it references NFPA 30, Flammable and Combustible Liquids, and NFPA 30B, Manufacture and Storage of Aerosol Products, for this information.

Q. What effects does fire hazard have on sprinkler system design and installation?

A. Fire hazard has a significant impact on sprinkler system discharge criteria, particularly the amount of water the sprinkler system needs to discharge to control or suppress the fire. With the possible exception of some extra hazard occupancies, storage operations present more challenging fire hazards than those found in non-storage facilities and will typically require more demanding discharge criteria. 

Determining the fire hazard also has an impact on other design considerations, such as the number of systems needed, sprinkler selection, sprinkler spacing, the need for hose connections, and water supply requirements. For example, individual sprinklers are required to cover smaller floor areas in storage facilities, so more sprinklers will be required on each system. Additionally, more systems will be needed because systems that protect storage facilities can cover no more than 40,000 square feet (3,716 square meters) as compared to the 52,000 square feet (4,831 square meters) most systems protecting other commercial, residential or assembly facilities can cover.

Q. What physical characteristics set storage facilities apart form non-storage facilities?

A. Storage height, size of the storage area, and the use of the facility are all factors. Al storage height of 12 feet (4 meters) has traditionally served as a demarcation point. Under the current rules, however, storage height and size of the storage area have become less of a factor.

NFPA 13 requires any storage operation, regardless of storage height or size, to classify fire hazard according to the commodity classifications. For example, a warehouse that sores paper products, such as books and stationery, to a height of 10 feet (3 meters) should be protected in accordance with the requirements for Class III commodities, even though the storage height doesn't exceed 12 feet (4 meters).

The size of a storage area affects the probability that a fire will start in the storage area, but doesn't impact the needed level of protection. It's often mistakenly assumed that a fire in a storage area will involve the full sprinkler design area. However, full-scale fire tests have shown that the actual fire area for a typical storage configuration where all sprinklers in the 2,000 square feet (186 square meters) design area operate is no greater than 200 square feet (18 square meters). So as little as 200 square feet (18 square meters) of storage can develop the same initial fire challenge as 2 million square feet (185,806 square meters).

Q. What is miscellaneous storage?

A. Before publication of the 1999 edition of NFPA 13, miscellaneous storage served as the demarcation point at which a certain size storage space could b protected in accordance with NFPA 13, without having to comply with one of the NFPA 231 series. Miscellaneous storage was limited to storage of a certain configuration, height, and floor area.

The criteria for protecting miscellaneous storage is now the same as the criteria for protecting storage up to 12 feet (4 meters) regardless of the size of the storage area or the manner in which commodities are stored.

Q. How should the sales areas of a mercantile facility by classified?
A. The sales areas of mercantile facilities, such as department stores, in which products are displayed up to 12 feet (4 meters), needn't be protected in accordance with the criteria for commodity classifications. Traditional mercantile operations fall within the ordinary hazard Group 2 classification and are identified as such in the appendix of NFPA 13.

Where mercantile operations store and display products are more than 12 feet (4 meters), the space must be protected for the appropriate commodity classification. Regardless of the height of product stored and displayed, the products may also need to be categorized according to special hazards, in accordance with Section 7-10.

Q. What about small storage rooms and closets?

A. In most cases, the contents of small storage rooms functioning as closets, don't need to have their contents classified according to the commodity classifications, provided storage heights are not more than 12 feet (4 meters) high. Application of the appropriate occupancy hazard is sufficient. However, the storage of plastics and Class IV commodities require special consideration, as indicated in Table 7-2.3.2.2.

Q. Are there any conditions under which storage facilities can be protected in accordance with the occupancy hazards, rather than than commodity classification?

A. For the miscellaneous storage of plastics, Class I, II, III and IV commodities, rubber tires, and rolled paper or where such commodities are stored no higher than 12 feet (4 meters), discharge criteria is permitted in accordance with the occupancy hazards identified in Table 7-2.3.2.2.

Q. What about requirements for small hose?

A. Where storage is Class I, II, III and IV commodities doesn't exceed 12 feet (4 meters), hose connections that supply small hose aren't required. However, the total combined inside and outside hose demand must be in accordance with Table 7-2.3.1.1. Storage of more than 12 feet (4 meters) and the storage of other commodities require small hose for first-aid, firefighting, and mop-up operations. 

Q. Where rack storage is involved, are in-rack sprinklers always necessary?
A. There are many cases where NFPA 13 doesn't require in-rack sprinklers for rack storage. The need for in-rack sprinklers depends on a number of factors, including the commodity stored, storage height, and encapsulation of products, type of sprinklers used, and the discharge criteria of the ceiling system. 

Q. Does NFPA 13 offer more than one design option for protecting storage facilities? 

A. Depending on the commodity stored and the storage arrangement, several options for sprinkler protection can exist. For example, 20 feet (6 meters) of storage of Class III commodities can be protected with a sprinkler system consisting of standard spray sprinklers at the ceiling only, a combination of ceiling sprinklers and in-rack sprinklers, or a ceiling only system consisting of either large drop or ESFR sprinklers.

It's important to note that each design option offers its own advantages and disadvantages, and that the level of protection offered by each design option is not necessarily the same. Ultimately, the decision is based on the needs of the user regarding which NFPA 13 design option to employ.

Summary NFPA 13 and Storage Facilities:

Designing and installing sprinkler systems for storage facilities has become rather complex. Nevertheless, any fire safety plan for a storage facility must include a sprinkler system. NFPA doesn't address the fire protection of storage facilities without the use of a sprinkler system.

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