7371 UNDERGROUND FIRE HYDRANTS - NEW SECTION
NEW MASTERSPEC SECTION
Published 1 June 2016
Introducing a new Masterspec section 7371 UNDERGROUND FIRE HYDRANTS which is based around NZS 4522:2010 Underground fire hydrants and relates to the design, fabrication and installation of underground fire hydrants. It includes:
- Screw-down hydrants (most common type)
- Gate valve hydrants (for specific conditions if screw-downs unsuitable)
- Water supply requirements
The primary function of fire hydrants to NZS 4522, is to provide an adequate firefighting water supply to the New Zealand Fire Service (NZFS). Adequate firefighting water supplies, for each risk classification, are specified in SNZ PAS 4509:2008 New Zealand Fire Service Firefighting Water Supplies Code of Practice.
In urban areas most hydrants are in the street and owned by a water supply authority.
Water supply (including hydrants) for fire fighting purposes applies to virtually all buildings in all situations, this includes houses in urban and rural areas.
PUBLIC AND PRIVATE FIRE HYDRANTS
There are two ownership types of hydrants to SNZ PAS 4509:
- Fire hydrant: An assembly usually contained in a pit or box below ground level and comprising a valve and outlet connection from a water main, to permit a controlled supply of water for firefighting.
- Private fire hydrant: An approved fire hydrant not owned by a water supply authority.
LOCATION OF HYDRANTS
SNZ PAS 4509 sets out spacing of hydrants (135m apart) and distances from buildings, 135m for required flow and 270m for additional flow if required. Distances from buildings are measured from the main entrance and in some cases additional entries.
In urban areas smaller sites with low rise buildings next to roads can usually depend on the street hydrants. However very large sites or sites off a long private road/ROW may not meet the distance requirements from street hydrants. In non-compliant cases private hydrants may have to be considered.
SNZ PAS 4509 also provides details on alternative (non-hydrant) water supplies, which are particularly useful for rural situations where there are no hydrants or low capacity hydrants.
Besides the location of hydrants, SNZ PAS 4509 also sets out number of hydrants and the water flow required from the hydrants. Compliance requirements are set out in SNZ PAS 4509 tables 1 and 2 or for specific design water flows to SNZ PAS 4509 Appendix H & J.
In line with this NZS 4522 specifies the dimensional, material, installation, and performance requirements for screw-down and gate valve underground fire hydrants used in New Zealand.
SNZ PAS 4509
This code of practice SNZ PAS 4509 is non-mandatory and is vaguely applied through local government requirements, so application on projects can be patchy. However it is a good guide and from a health and safety in design sense, worth taking into account.
SNZ PAS 4509:2008 New Zealand Fire Service Firefighting Water Supplies Code of Practice is unusually a publicly available specification and is free to download at.