Standpipes

A standpipe is a system of pipe that delivers a water supply for hose connections and automatic sprinklers in combined systems.

standpipe system diagram

Courtesy of MeyerFire

Standpipe systems are typically installed vertically from floor to floor but are considered horizontal when two or more hose connections are installed on a single level.

 

System Working Pressure -The maximum anticipated static (nonflowing) or Residual (flowing) pressure applied to the standpipe system, exclusive of surge pressures but inclusive of the system design/demand pressure from the fire department connection (FDC).

TYPES OF STANDPIPE SYSTEMS 

There are different types of standpipe systems, each designed to meet specific fire protection needs. Below is a detail of the different systems and how they operate as well as the three different classes and their purposes.

Automatic Wet Standpipe System – Has a permanently attached water supply capable of automatically supplying the system demand at all times. The pipe contains water and requires no action other than opening the hose valve.

Automatic Dry Standpipe System – Has a permanently attached water supply capable of automatically supplying the system demand at all times. The pipe contains air or nitrogen and requires no action other than opening the hose valve, which when released, allows water to flow into the pipe and out of the hose valve.

Semi-Automatic Dry Standpipe – Has a permanently attached water supply capable of automatically supplying the system demand at all times. The pipe contains pressurized air or nitrogen, commonly using a deluge valve and requires a remote-control device to provide water at the hose valve.

Manual Wet Standpipe – Contains water, typically used to provide fire sprinkler demand in a combined system but relies exclusively on the fire department to provide standpipe system demand (pressure and flow) from the fire department connection (FDC).

Manual Dry Standpipe – A standpipe system with no permanently attached water supply that relies exclusively on the fire department to provide standpipe system demand (pressure and flow) from the fire department connection (FDC).

Combined System – A standpipe that supplies both hose connections and automatic sprinkler systems. It can include manual wet or automatic wet standpipe systems.

CLASSES OF STANDPIPE SYSTEMS

Class I – 2 ½ inch fire department connections that provide the required pressure and flow for structural firefighting.

Class II – 1 ½ inch legacy hose connections used by trained occupants or fire brigade for incipient fire control.

Class III – Combination of 2 ½ inch fire department hose connections used for structural firefighting and legacy 1 ½ inch hose connections used by trained occupants or fire brigade for incipient fire control.

TESTING of STANDPIPE SYSTEMS

NFPA 25 Standard for the Inspection, Testing and Maintenance of Water-Based Fire Protection Systems, provides specific instructions when it comes to the testing of these systems. Below are some of the specific requirements for flow testing and general guidance on standpipe systems.

Flow testing 

Five-year full flow test of automatic standpipe

500 GPM minimum at most remote hose connection(s)

250 additional GPM simultaneously for each additional standpipe until system demand is flowing

System demand is based on the standard and code editions adopted at the time of   installation

Typically system demand is as follows.

1000 gpm maximum flow, in a building fully sprinklered throughout, with a sprinkler system designed to the requirements of NFPA 13 Standard for the Installation of Sprinklers and 1250gpm for buildings that are not sprinklered throughout in accordance with NFPA 13.

Pressure

100 psi minimum hose outlet pressure with a maximum of 175 psi for buildings post 1993 edition of NFPA 14 Standard for the Installation of Standpipe and Hose Systems.

65 psi minimum hose outlet pressure with a maximum of 100 psi for buildings prior to 1993 edition of NFPA 14.

Hose Valves

Hose valves on Class I and Class III standpipes shall be tested annually by fully opening and closing the valve.

Pressure-Regulating Valves (Direct acting)

Both Pressure-reducing Valves (PRV) and Pressure-Restricting Devices (PRD) are required to be flow tested every five years and compared to previous test results. Adjustments shall be made in accordance with the manufacture’s instructions.

A tag shall be attached to the valve indicating the test date, flow, and both inlet and outlet pressure recorded during the test.

 Flow testing requirements  

All Automatic and semi-automatic Standpipe systems shall be flow tested every five years.

Manual Dry Standpipes shall be hydrostatically tested every five years to not less than 200 psi for 2-hours, or at 50 psi in excess of the maximum pressure, where the maximum is in excess of 150 psi,

Manual Wet Standpipes that are part of Combined sprinkler/standpipe systems are not subject to flow testing requirements found in NFPA 25.

Fire Department Connection (FDC)

Piping from the FDC to the check valve shall be hydrostatically tested at 150 psi for two hours at least every five-years.

The National Fire Sprinkler Association’s Expert can Answer Your Questions about Standpipe Systems

The National Fire Sprinkler Association’s team of experts is available to address questions regarding anything in fire protection. These experts actively participate in NFPA technical committees and contribute to the development of industry standards. For detailed information on standpipe systems, their design, installation, and maintenance, ask our Expert of the Day.

Further Reading on Standpipes

COMBINATION SPRINKLER STANDPIPE SYSTEMS: YOU MIGHT BE SURPRISED

STANDPIPE SYSTEM WORKING PRESSURE