Issue 24 – February 2011
The simplest, most efficient, and cost-effective solution to house fires is a home sprinkler system. This can now be integrated into the domestic plumbing.
Without fire, survival would be a supreme challenge. Its creation and control is thought to be one of humankind's first inventions and has allowed us to build our own environment.
But fire can be both friend and foe. In our built environment, the risk from fire is greatest in the home. The New Zealand Fire Service combats over 3,500 reported house fires every year, many resulting in complete destruction.
A well-proven solution to help reduce this problem has been at our fingertips for well over 100 years. Fire sprinkler technology was first used to protect specialised industrial buildings in the 1880s and is now commonplace throughout the commercial world. It has been so successful that it is now rare to find some types of building without this technology specified for it.
Sprinklers integrated in house plumbing
There are many misconceptions about home fire sprinkler systems – most people still have a commercial mindset. NZS 4517:2010 Fire sprinkler systems for houses doesn't give a simple definition either. It has to address design flexibility for the myriad of ways this technology can be applied.
Luckily, the ideal home fire sprinkler solution is simple, cost-effective, and efficient. All it takes is a rethink of how a house is plumbed. A home fire sprinkler system no longer has to be an independent sprinkler system added separately inside a house. It can be integrated into what is best termed 'well designed house plumbing', incorporating all the domestic water supply requirements in the one system.
Redesigning domestic plumbing to include sprinkler technology radically improves both water quality and flow. For example, with these systems, you are no longer likely to get a poorly performing shower.
Simplicity is the key
Such a solution sounds common sense, but what does one of these redesigned domestic plumbing systems look like?
Simplicity is again the key. From the water feed into the house, a loop of supply pipe is run in the ceiling space (on each floor level) close to the centre line of the rooms. All the water needs are then drawn from this loop. The design must centre on the needs of the sprinkler heads, as these have the greatest water demand.
Although simple, these systems must still be properly designed. Sprinkler heads must meet stringent minimum flows to conform to their manufacturer's testing requirements.
Often only a single sprinkler head is required to protect a whole room, as coverage areas can be as large as 6 m x 6 m. However, NZS 4517:2010 requires the design to satisfy a two sprinkler-head flow rate where more than one is present in the same room.
Typically, a sprinkler head requires approximately 60 litres of water per min (or 1 L/s). Depending upon design, there are models available that can reduce this to 37 L/min.
Requirements include flow tests
This technology now fully integrates into the domestic plumbing of a house. The main requirements of these systems are that they must:
- be specifically designed
- accurately show the locations of all the sprinkler heads
- be flow tested after installation
- come with a maintenance manual.
The flow test involves timing the amount of water that the most hydraulically demanding sprinkler head(s) (usually in the open plan lounge area) discharge within 60 seconds. A wheelie bin can be effectively used for this.
Set it and forget it!
This technology is essentially a 'set and forget' system. When a tap is turned on that is connected to the loop on which all sprinkler heads are attached, the water will flow around the loop past each sprinkler head and validate that it has an available water supply.
The required sprinkler pressure must be obtained from your water supply. However, these systems can be incorporated into the domestic plumbing from any water supply, for example:
- direct connection off the street mains
- gravity tank
- tank and pump.
Evidence overseas suggests that this technology will become the norm for domestic plumbing. It can future-proof property, as well as maximise the value and efficiency of home fire prevention.
For more information visit http://homesprinklers.fire.org.nz.
© Build 121, December 2010/January 2011, BRANZ
This article was written by James Firestone, Fire Engineer, New Zealand Fire Service. This article was first published in Build magazine December 2010/January 2011 and is reproduced with permission from BRANZ.
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