AFSA AFSA
AFSA


Summary of Changes to NFPA 14, 2003 Edition


by J. Scott Mitchell, P.E. and Steve Leyton, from the 2/2003 issue of Sprinkler Age, page 10

Numerous changes were made to NFPA 14, Standard for the Installation of Standpipe and Hose Systems, that will be reflected in the forthcoming 2003 edition, due to be released in early April. The first noticeable change is in the title. "Private Hydrants" was removed since this criteria was sent back to NFPA 24, Standard for the Installation of Private Fire Service Mains and Their Appurtenances.

Manual of Style

In order to be acceptable as an ANSI standard, all NFPA standards are being revised in accordance with the criteria found in the Manual of Style.

- Two chapters are added.

- Definitions are in their own chapter.

- Metric units become primary to English units.

- The section number dash is deleted (3-4.4 becomes 3.4.4).

- Exceptions are eliminated (criteria presented in new subsections).

- "Appendix" is termed "Annex".

Water Supply

The current and previous editions of NFPA 14 only tell us when a manual standpipe cannot be used. Explicit permission to use this type of system is not given. For instance, NFPA 14:3-4.1 (2000 edition) prohibits the use of manual standpipe systems in high-rise buildings instead of giving permission for their use in low-rise buildings. Many have misconstrued this to mean that all standpipe system demands must be satisfied automatically (all standpipe systems have to have a fire pump), especially standpipe systems that share piping with automatic sprinkler systems. But this is simply not true. New criteria under system requirements will state that Class I standpipe systems in buildings not classified as high-rise buildings shall be permitted to be manual, automatic, or semiautomatic. New criteria under system design and sizing will allow that where a manual system is permitted and an attached water supply is provided to supply an automatic sprinkler system or to maintain water in a wet system, the attached water supply shall not be required to satisfy the standpipe system demand.

This is a significant clarification regarding combined standpipes and sprinkler risers. Specifically, it is where the water supply for the sprinkler system is automatic, but for the standpipe it is manual. Wording is added to the definition for a "manual-wet" standpipe to accommodate those systems that share a water supply with an automatic sprinkler system. The annex will explain that the intent is to permit the omission of a fire pump as part of the standpipe system when the automatic sprinkler system can be designed and installed with the available water supply and that the flow and pressure demands of the standpipe system can be provided by the fire department apparatus through the fire department connection. This has always been the intent of the standard, but has not always been explicitly stated.

Design Issues

There have been several changes to design requirements. One especially significant revision is within the definition of standpipe classes. For Class II and III systems, the term "building occupants" has been replaced by "trained personnel." The intent is that, unless a building occupant is properly trained to use the hose equipment, they should immediately evacuate the building.

It is a common practice in high-rise buildings to supply water to the fire sprinkler system through the standpipe system piping. This can be accomplished in several arrangements. One method is to supply the sprinklers on each floor through connections from a single standpipe. A second method is to supply sprinklers on alternating floors from a single standpipe while the other floors are supplied from another standpipe. A third method is to supply the sprinklers on each floor through connections from both standpipes. Changes taking place in this code cycle will affect and clarify these scenarios. One change will require a check valve at each connection, regardless of which of the three mentioned methods is used. The new text will read as follows.

- Valves on Combined Systems. Each connection from a standpipe that is part of a combined system to a sprinkler system shall have an individual control valve and check valve of the same size as the connection.

Currently, the requirement to have a check valve at each connection only applies to the third method mentioned above where the floor sprinklers are supplied by multiple standpipe connections. The intent is to prevent water flow alarm activation on multiple floors and to expedite system drainage when only one standpipe is taken out of service. With the new requirement for a check valve at each connection, the alarm concerns are addressed, and even from a single standpipe, the standpipe riser itself can be drained without draining each floor's sprinkler piping. Subsequently, NFPA 14:4-2.5.2 (2000 edition) is no longer necessary and is being deleted. The related appendix commentary indicated that combined automatic sprinkler and standpipe risers should not be interconnected by sprinkler system piping. After an extensive effort to determine the basis for such a comment, the technical committee voted to delete this text as well.

In current and previous editions the only criteria concerning lateral piping is the requirement that they be protected from fire, freezing, and mechanical damage. This implies that the minimum size for lateral piping is 4 in. per NFPA 14:5-6. This is not the case and is made evident by a couple of changes. The new definition for a branch line (formerly termed lateral piping) will be, "a piping system, generally in a horizontal plane, connecting one or two hose connections with a standpipe." New pipe sizing criteria will allow these "branch lines," serving two or less hose connections, to be as small as 21/2 in. if proven adequate by hydraulic calculations.

The definition for a standpipe will now include both vertical risers and the horizontal portions of standpipes that are the water supply for more than two hose connections on a single level. Prior to this change, horizontal standpipes commonly used in locations such as stadiums, transit system tunnels, and malls were not explicitly addressed. The intent of these changes collectively is to distinguish between a secondary line to one or two hose connections on a single floor, and the primary distribution system of risers and mains that may, occasionally be run on a horizontal orientatin. Where unique conditions require more than two outlets on the same level that can only be fed by a horizontal distribution system, the arrangement shall be considered a "horizontal standpipe."

Pressure Regulation

These paragraphs are rewritten. Hose connections available for occupant use that have static pressures exceeding 175 psi or residual pressures exceeding 100 psi will be required to have an approved pressure-regulating device to limit both the static and residual pressures (at the required flow) to 100 psi. Hose connections for fire department use that have static or residual pressures exceeding 175 psi must be provided with an approved pressure regulating device that will limit both the static and residual pressures (at the required flow) to 100 psi. There is really nothing new here; however, beware that not all pressure regulating valves will limit both static and residual flow. Some (i.e. pressure restricting valves) only regulate the residual pressure.

New criteria will also require that pressure regulation of water supplies be arranged such that no greater than 200 psi is permitted to be supplied to any connection and the next closest available hose connection in the event of a failure of any single pressure regulating device in the systems. The net effect of this new requirement will be to negate the viability of using a so-called "Master PRV" upstream of standpipe hose outlets, in favor of pressure regulating type devices at each connection. The committee's primary concern was the potential for over-pressurizing entire zones of a standpipe system and the attendant threat of to firefighter safety in such an occurence.

Installation Issues

There has never been an explicit requirement to install a main drain test connection for the purpose of testing the water supply connection. The next edition will call for one on each standpipe system. It is interesting to note that NFPA 25 calls for a main drain test to be conducted even though NFPA 14 did not require provisions for one to be installed.

Currently dry standpipes are not allowed to be concealed in building walls or built into pilasters (14:4-1.1). The intent here is to keep piping that has no water (leaking can be evidence of damage) visible for inspection. Changes to this section will allow this, provided the piping integrity is monitored with supervisory air pressure. If the piping is damaged and cannot maintain air pressure, notification will be given. Provisions for this supervisory function were added to the alarm section.

Hydraulic Calculation Issues

NFPA 14 will give a maximum required flow for each outlet. Currently it requires a minimum of 500 gpm to be provided from the hydraulically most remote standpipe and 250 gpm for each additional standpipe. It further prescribes that the pipe sizing be based on providing 250 gpm at the two hydraulically most remote hose connections on the standpipe and at the top most outlet of each of the other standpipes. Some have misapplied this criteria and have required 500 gpm at the single hydraulically most remote outlet. The new paragraph will read as follows.

- The maximum flow to be demonstrated from a single hose connection shall be 250 gpm for a 2.5-in. connection and 100 gpm for a 1.5-in. connection.

There are also special hydraulic calculation procedures for horizontal standpipes. They will require that where a horizontal standpipe on a Class I and Class III system supplies three or more hose connections on any floor, hydraulic calculations and pipe sizes for each standpipe shall be based on providing 250 gpm at the three hydraulically most remote hose connections on the standpipe and at the topmost outlet of each of the other standpipes at the minimum residual pressure required. The total flow is still required to be up to 1,250 gpm (1,000 gpm when sprinklered.)



ABOUT THE AUTHORS:



J. Scott Mitchell, P.E. is a fire protection engineer with AFSA's Technical Services Department. He earned his B.S. degree in engineering technology from Oklahoma State University. Mitchell sits on several NFPA technical committees, including NFPA 13 hanging and bracing, and is a member of SFPE and NFPA.



Steve Leyton is president of Protection Design & Consulting, San Diego, Calif. Now in his twenty-second year in the fire sprinkler industry, He started Protection Design & Consulting in 1995, and has focused the firm's work on architectural and contracting clients. Leyton is a member of AFSA; NFPA; the California Fire Prevention Officers, Northern and Southern Sections; and the San Diego Fire Protection Association. He is AFSA's alternate member on the NFPA 14 Technical Committee. Leyton has worked on all manner of projects including residential, commercial, industrial and high-rise, in both the United States and Mexico.



<< Previous Article Next Article >>


AFSA
Home | Copyright © AmericanFire Sprinkler Association. All rights reserved.
Contact Us Search AFSA Store Downloads Join AFSA