FIRE HYDRANT SYSTEMS FOR BUILDINGS - NEW SECTION
NEW MASTERSPEC SECTION
Published 1 June 2016
Introducing a new Masterspec section 7372 FIRE HYDRANT SYSTEMS FOR BUILDINGS which is based around NZS 4510 Fire Hydrant Systems For Buildings and relates to the design, approval, installation and commissioning of fire hydrant systems for buildings.
The primary function of these fire hydrant systems to NZS 4510, is for fire service use when attending and dealing with fire emergencies in buildings. These consist of a hydrant main (pipe) installed in a building and usually permanently charged with water from a pressurised supply sufficient for fire fighting. The pipe has a building hydrant inlet (BHI) on the outside of the building and a number of building hydrant outlet assemblies (includes landing valves) at specified points, usually on the inside of the building. The fire service pumping appliances (usually the fire engine) connects to the BHI, water is reticulated to building hydrant outlets (usually landing valves) to which hoses can be connected. Where the pressure available from fire service pumps is not able to deliver the required flow pressures, built in booster pumps will be required.
Fire hydrant systems generally mean that fire fighters can deploy more quickly, efficiently and safely within a larger building, and have a more dependable water supply closer to the fire.
CHARGED HYDRANT MAIN
Charged hydrant main, Charged riser and Wet riser, amount to much the same thing being the pipe that is kept charged with water. The only difference being risers are largely vertical and mains more neutral on their direction. These are the types that NZS 4510 covers. Uncharged risers (dry risers) are not covered by NZS 4510 and generally no longer permitted for new buildings, except where specifically designed for special purposes and approved by the hydrant system certifier.
DESIGN AND CERTIFYING
Hydraulic design of the system is to be by a suitable qualified Design Engineer.
A Hydrant System Certifier (HSC) must to NZS 4510:
- certify the final system construction/installation
- approve the ongoing testing & maintenance contract
- provide preliminary approval of basic (system) design decisions
BUILDING CODE REQUIREMENTS
The requirements to provide fire hydrant systems for buildings is derived from NZBC C Protection from Fire, in particular, directly from NZBC C/AS2 to C/AS7 section 2.2 Fire Safety Systems, and by specific design from NZBC C/VM2, 4.8 Design Scenario FO (to satisfy C5.5).
Fire hydrant systems are not described, like most other fire safety system types, in NZBC F7 Warning Systems, it is described in Acceptable Solutions Appendix A, A2.1 and defined as:
Type 18 – Fire hydrant systems for buildings
Fire hydrant systems shall comply with NZS 4510.
Only NZBC C/AS1 (SH) has no requirements for fire hydrant systems. All other Acceptable Solutions have requirements but sometimes allow one or two exemptions under section 2.2:
- Type 18 building fire hydrant system, unless the Fire Service hose run distance from Fire Service vehicular access to any point on any floor is less than 75 m. or,
- Type 18 building fire hydrant system in all cases where the height from the Fire Service attendance point to any floor is greater than 15.0 m. Otherwise, a Type 18 system is required unless the Fire Service hose run distance from Fire Service vehicular access to any point on any floor is less than 75 m.
The Acceptable Solutions Table 2.0 is a convenient reference showing a range of building conditions and fire systems required.
LOCATION OF HYDRANTS
Hydrant locations to NZS 4510.
NZBC requires the building hydrant inlet (BHI) shall have ready access from street level and be protected from the effects of fire including debris falling from upper floors.
NZS 4510 indicates in multi-storeyed buildings locate building hydrant outlets (landing valves) within a protected lobby. Location within stairwells, while permissible, creates congestion in a fire, and reduces the effective reach of standard length hose lines because of the need to base the fire attack from the landing below.
Hydrants can form part of the buildings fire hose reel supply.
For some location/spatial requirements refer to NZS 4510:
- Figure 4 – Measurement of hose lengths
- Figure 5 – Outlet assembly spatial requirements
- Figure 6 – BHI standard requirements (BHI Building hydrant inlet)
DURING CONSTRUCTION OR DEMOLITION
It is recommended that internal building hydrant systems should be operational during both construction and demolition periods as both activities provide a heightened risk of fire. NZS 4510 specifies that during construction, the hydrant system must be enlivened progressively (including pumps, if required) as construction advances.