Standpipes for Fire Suppression: An Introduction

Hope your week is going very well.

This week I'd like to open a short series on standpipes. Today's article is a basic overview of some basic requirements associated with standpipes used for fire suppression.

Basic components of a standpipe for fire suppression.

Purpose
Standpipes are used to support manual firefighting efforts by delivering water to hard-to-reach areas of a building. The intent of a standpipe system is to avoid having to distribute and connect hundreds of feet of hose for a single interior attack by firefighters.

Hard-to-reach areas of a building aren't confined to one direction. Buildings which are very tall (highrises) or are deep underground, or are very wide by nature could all have portions of the building which would be difficult to reach.

Applicable Codes & Standards
In the US, the International Building Code (IBC) and International Fire Code (IFC) are often the first stop for standpipe requirements. While the two codes mirror each other, the International Building Code requires standpipes based on:

• height (a story located more than 30 feet above the lowest level of fire department access, or 30 feet below the highest level of fire department access) (see IBC Section 905.3.1)
• unsprinklered assembly occupancies (see IBC Section 905.3.2)
• covered and open mall buildings (see IBC Section 905.3.3)
• stages (see IBC Section 905.3.4)
• underground buildings (see IBC Section 905.3.5)
• helistops and heliports (see IBC Section 905.3.6)
• marinas and boatyards (see IBC Section 905.3.7)
• rooftop gardens and landscaped roofs (see IBC Section 905.3.8)

Once it has been determined whether a standpipe system is required or not, the IBC and IFC defer to NFPA 14 to prescribe how the system is to be installed.

Class of Standpipes
Standpipes can be classified in several areas. The first is the class of standpipe, which relates directly to the hose connection type and the intended user. Based on 1-1/2 inch hose failures and the associated testing that goes along with them, 1-1/2 inch hose stations are much less common today.

I've found many situations with sprinklered buildings where hose stations have been removed as they are no longer required and are a burden for testing and maintenance. Here are the standpipe classifications, with Class I being by far the most common in the US today:

• Class I: provides 2-1/2 inch (64 mm) hose connections for fire department and trained use.
• Class II: provides 1-1/2 inch (38 mm) hose stations to supply for building occupants or initial fire department response
• Class III: provides 1-1/2 inch (38 mm) hose stations for building occupants and 2-1/2 inch (64 mm) hose connections for fire department and trained use

Types of Standpipe
The other defining description for standpipe is when water is delivered, and at what relative pressure. Types of standpipes include:

• Automatic dry: normally filled with pressurized air where water is delivered automatically when a standpipe hose cap is removed. The water, when delivered, is capable of supplying the system demand.
• Automatic wet: normally filled with water capable of supplying the system demand automatically.
• Manual dry: normally filled with air and without a permanent water supply. Water is required from a pumper truck in order to meet system demand.
• Manual wet: normally filled with water that is not at a pressure capable of supplying the system demand. Manual wet systems require  water to be pressurized by a fire department pump in order to meet system demand.

Components of a Vertical Standpipe
Standpipes are not always vertical standpipes, but for multi-story buildings they are the most prevalent and are the topic of discussion this week.

Flexible Coupling

• Purpose: Flexible couplings are included near floor levels to prevent catastrophic damage to the suppression system from the building structure while the building structure is moving in an earthquake. Flexible couplings allow the vertical pipe within a standpipe (or sprinkler system) to tolerate the horizontal building movement and still stay connected.
• Where Required: Within 12 inches above and 24 inches below floor level in multi-story buildings. [NFPA 13 2002-16 9.3.2.3(2), 2019 18.2.3]
• When Required: When the building requires seismic protection (seismic design category C, D, E, or F). Couplings are also provided at each floor level (often just above the floor level) to aid in installation.

Isolation Valve

• Purpose: Standpipe isolation valves allow shutdown of a single standpipe without interrupting the water supply to other vertical standpipes. This can play an important role with maintenance, repair, modification, or during active firefighting scenarios.
• Where Required: Isolation valves are required on all standpipes (including dry standpipes). [NFPA 14 2003 6.2.2, 2007-19 6.3.2]

Penetration Clearance

• Purpose: Clearance around floor penetrations are important for seismic bracing, again to prevent damage to the system from the building structure during an earthquake.
• Size: The diameter of the hole or sleeve must be 2-inches larger for pipes 1 to 3-inches in diameter, or 4-inches larger than the pipe for pipe 4-inches or larger in diameter. [NFPA 13 2002-16 9.3.4.2 and 9.3.4.3, 2019 18.4.2 and 18.4.3]
• Where Required: Where pipe passes through platforms, foundations, walls or floors, except where flexible couplings are located within 1-foot of each side of the penetration. [NFPA 13 2002-16 9.3.4.5, 2019 18.4.5]

Pressure Gauge

• Size: Not smaller than ¼-inch (6 mm). [NFPA 14 2003 5.6.1, 2007-19 5.5.1]
• Where Required: For standpipes, a pressure gauge is required at the top of each standpipe. [NFPA 14 2003 5.6.1, 2007-19 5.5.1]

Riser Clamp

• Purpose: Riser clamps are used to provide support to vertical pipe.
• Where Required: Within 24-inches (610 mm) of the centerline of the riser, to support the riser horizontally. In multi-story buildings, riser supports are required at the lowest level, at each alternate level, above and below offsets, and at the top of the riser. [NFPA 13 2002 9.2.5.3.1, 2007-16 9.2.5.4.1, 2019 17.4.5.4.1] Support above the lowest level to prevent movement upward when flexible fittings are used. [NFPA 13 2002 9.2.5.3.2, 2007-16 9.2.5.4.2, 2019 17.4.5.4.2]

Standpipe Hose Connections

• Purpose: To provide a point of connection for firefighters to connect hoses and get water to manually fight the fire.
• Where Located: At 3-feet (0.9 m) to 5-feet (1.5 m) above floor level. [NFPA 14 2003 7.3.1, 2007-19 7.3.1.1]
• Where Required: We’ll explore this in greater detail in the articles to come. There's volumes of information about these requirements, but for reference be sure to check NFPA 14 2003-19 7.3.2-7.3.4 and IFC 905.4-905.6.

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