Which system does not have a permanent water supply and is designed to have water only when the system is being supplied through the FDC?

Try the new Google Books

Check out the new look and enjoy easier access to your favorite features

Standpipes are a critical tool that require preplanning on first responding apparatus in order to be used effectively. The initial approval process for these systems is critical and the fire prevention bureau can assist responding crews by ensuring proper installation and maintenance of these systems. Standpipe systems vary in design, use, and location. These factors vary based on the adopted code; the use, size, and type of building they are installed in. Typically, model codes refer to NFPA 14, Standpipe and Hose Systems for the design, installation, and maintenance of these systems.

Standpipe systems are a series of pipe which connects a water supply to hose connections that are intended for fire department or trained occupant use. At times building are provided with only piping for the standpipe system. Many current designs include a combination system which supplies the sprinkler system and standpipe system. The location of hose connections varies (based on adopted fire and building codes per the local authority having jurisdiction) and can include stairways on buildings over 30 feet in height, Group A occupancies with occupant loads over 1,000 persons, covered malls, stages, underground buildings, or heliports.

Codes will speculate the type of system that will be installed and where the hose connections shall be located. Section 905 of the International Fire Code (IFC), 2006 edition spells out the requirements of when and where standpipe connections are required. The IFC would require a standpipe system in a building where the floor level of the highest story is located more than 30 feet above the lowest level of fire department access. The code would also give requirements on the location of hose connection to be located at an intermediate floor level landing between floors unless an alternate location is approved by the authority having jurisdiction (AHJ). Once the adopted code states a system is required the designer and AHJ would go to the referenced standard to determine the design requirements.

Model fire and building codes give the requirements for when standpipe systems are installed. The specific type of system is based on the occupancy classification and building height. Standpipes have three major classifications:

• Class I standpipes serve a 2.5-inch fire hose connection for fire department use. These connections must match the hose thread utilized by the fire department and are typically found in stairwells of buildings.
• Class II standpipes serve a 1.5-inch fire hose connection and are typically found in cabinets. These are intended for trained occupant use and are spaced according to the hose length. The hose length and connection spacing is intended for all spaces of the building.
• Class III standpipes have both connections of Class I and II. Many times these connections will include a 2.5-inch reducer to a 1.5-inch connection.

NFPA 14 is the standard which the system shall be designed, installed, and maintained to. The correct edition should be correlated with the adopted code of the jurisdiction Once it is determined that a standpipe system is required, the type of system should be determined. These types include:

• Automatic Standpipe systems are designed to provided the need pressure and water supply when the valve is opened.
• Automatic Dry Standpipe system is only designed to have water in the system piping when the system is in use.
• Manual Dry Standpipe system are exclusively for fire department use and require a fire department pumper to supply the need pressure and water supply through a fire department connection.
• Semi-Automatic Standpipe System are capable of providing the need pressure and water supply, after the activation of a control device or fire pump.
• Wet Standpipe systems are wet at all times.

Systems design has changed over the years. In previous versions of NFPA the design pressure for Class I and III systems was based on a residual pressure of 65 psi at the most hydraulically remote connection. In the current editions of NFPA 14, the design pressure is based on a residual pressure of 100 psi. Plan reviewers, fire marshals, or inspectors must be cognizant about their department response when approving standpipe systems. The local AHJ is permitted to reduce the pressure requirements based on local response requirements. The design pressure should be based on the amount of hose and nozzle type the first arriving company will be deploying in a fire situation.

Many buildings are required to have an Automatic Class I standpipe system with a design pressure of 100 psi. Based on friction loss, municipal water supply, and pressure loss for the height of the standpipe a fire pump may need to be designed into the system. Due to the pressure requirements standpipes are limited to a maximum height of 275 feet. Those buildings over 275 feet in height will require the standpipe systems to be split in different pressure zones.

Due to the higher design pressures at lower floors, standpipe systems may include the use of pressure reducing valves. These valves must be inspected at the time of acceptance testing and on a regular basis. Responding fire fighters must be aware of these devices and their use. This became apparent in the One Meridian Plaza Philadelphia, Pennsylvania on February 23, 1991. The technical report produced by the United States Fire Administration summarized the difficulties as :

"Improperly installed standpipe valves Pressure Reducing Valves (PRVs) provided inadequate pressure for fire department hose streams using 1 3/4-inch hose and automatic fog nozzles. Pressure reducing valves were installed to limit standpipe outlet discharge pressures to safe levels. The PRVs were set too low to produce effective hose streams; tools and expertise to adjust the valve settings did not become available until too late."

The plan review process and initial acceptance testing of standpipe systems is critical for system performance. The plan review process must ensure that the system type matches the requirements of the adopted code. The details of the water supply shall be provided and the test should be conducted within the last year. The plan review must include a detail check of the location of hose connections, and review the supplied calculations to ensure that minimum or maximum pressures are not exceeded. The plan reviewer must require detailed information on pressure regulating devices and specify the type of threads found on the connections.

Initial acceptance testing is very similar to that of automatic sprinkler systems. These tests will include flush test, a hydrostatic test, and end with a flow test. The equipment required for the testing shall be provided by the contractor. Acceptance testing of some standpipe systems may require the use of the first arriving pumper to supply the needed pressure through the fire department connection.

When the final acceptance testing is conducted or during the flow test that the first or second arriving engine companies be involved in the testing. This involvement will ensure the proper thread type has been used, and necessary flow requirements are meet. The involvement of the first arriving companies will become a beneficial training session for all of the fire fighters involved. The fire fighters should identify the type of system present, the pressure setting of pressure reducing valves, location of fire pumps, location of hose connections, and the location of the fire department connection. These devices should then be added to the pre-incident survey.

Related links:

Understanding combination sprinkler standpipe systems is simple. The fire sprinkler system and standpipe system share a common riser. Section 3.3.20.3 of the 2019 edition of NFPA 14: Standard for the Installation of Standpipes and Hose Systems defines a combined system as:

A standpipe system that supplies both hose connections and automatic sprinklers.

That definition also holds a hidden clue to understanding the design implication of a combined fire sprinkler system and standpipe system. While it states “automatic sprinklers,” it does not reference the type of required standpipe activation. That leads us to a discussion of the different kinds of standpipes systems and their unique characteristics.

Types of standpipes in combination systems

The 2019 edition of NFPA 14 defines seven different types of standpipes systems:

• Automatic dry standpipe system
• Automatic wet standpipe system
• Combined system
• Manual dry standpipe system
• Manual wet standpipe system
• Semiautomatic dry standpipe system
• Wet standpipe system

However, only certain types of standpipe systems can be combined with fire sprinklers. We can quickly eliminate a manual dry standpipe system, as it does not have a permanent water supply capable of supplying our automatic sprinkler design. The semiautomatic standpipe system is simply eliminated by the “automatic” sprinkler requirements found in NFPA 13: Standard for the Installation of Sprinkler Systems. 

The combined system and wet systems are obvious choices and only indicate that the risers are shared wet risers. This essentially leaves us with a choice between automatic dry standpipe, automatic wet standpipe, and a manual wet standpipe system—the key difference being the choice between automatic and manual. The term “automatic” simply means that the system will automatically provide required pressure and flow while, in contrast, the “manual” system water supply is only required to meet sprinkler demand. The manual standpipe side of the system will require supplemental pressure and flow to be supplied by the fire service.

Hose connections in combination systems

For this discussion, one must also understand that while hose connections are found in combination systems, hose connections may not always be required to meet both the flow and pressure requirements of a class I or III standpipe system. It must also be noted that combination systems are not allowed in all occupancies. Combined-riser-designed systems are typically found in large or multiple floor-structures below the local jurisdiction’s height limitations for high-rises.

Choosing the right combination sprinkler standpipe system

The choice of a manual wet set-up supplementing a combination standpipe system over an automatic wet is used to reduce total system cost by relying on the fire service to provide pump pressure. This allows a mid-rise building to be constructed without the need for a building fire pump. This often comes as a surprise to the fire service, which often believes that all standpipe hose connections are created equal when it comes to pressure and flow requirements. There must be a clear strategic plan for the use of combination systems, and fire service tactical considerations must start with the building’s system design.

The local officials, both fire service and building officials, must understand local capabilities and have an in-depth understanding of the design differences and implications to be able to adequately provide the best level of fire protection for their communities.

Have more questions about combination sprinkler standpipe systems? NFSA members can reach out via our website or by calling 443-863-4464 for answers and support from our code, standards, and engineering experts. Not an NFSA member yet? Join today!

EXPLORE NFSA MEMBER BENEFITS

For over a century, the National Fire Sprinkler Association (NFSA) has served as the voice of the fire sprinkler industry. Our mission: advocating to protect lives and property through the widespread acceptance of the fire sprinkler concept. To join NFSA or learn more about the ways membership can benefit your organization, visit nfsa.org/join.