Scope of NZS 4517

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There are instances where these systems are being installed outside the scope of NZS 4517 into buildings for the protection of property, including marae and community halls. The residential heads used in these systems are not designed and tested for the fire loads and configurations in such occupancies. While some designers may attempt to compensate by allowing for additional heads to operate, there is no assurance that they will be effective in such buildings.

In addition, there are instances where NZS 4517 fire sprinkler systems are being installed where sprinkler protection is specified by Acceptable Solutions and Verification Methods, for example, in rest homes and backpackers' lodges. These buildings should have a sprinkler system designed in accordance with NZS 4515 or NZS 4541, as required by the fire safety Acceptable Solutions and Verification Method. These systems have to be maintained in accordance with a compliance schedule.

Water pressure losses

As these residential sprinkler systems are often connected to domestic water supplies, their water supply is often metered. A typical 20 mm or 25 mm domestic water meter will not normally allow an adequate flow of water for NZS 4517 fire sprinkler systems. Designers of NZS 4517 fire sprinkler systems need to check that there is an adequate flow of water. Invariably, a larger meter will need to be installed to achieve a greater flow of water. If an undersized meter is installed, the NZS 4517 fire sprinkler system will not effectively control the fire. A similar effect will result if the pipe material and size is not installed as per the design.

Sprinkler systems for homes and legal requirements

The installation of NZS 4517 fire sprinkler systems, which are connected to a potable water supply, is plumbing work, and must be carried out under a building consent. The building consent authority (BCA) must ensure that the system complies with the building consent before issuing the code compliance certificate. The NZS 4517 fire sprinkler system must be commissioned and tested according to Appendix F of the Standard by using a simple 'bucket test'. This test involves removing the two hydraulically most remote sprinkler heads and timing the water discharge into a graduated 100-litre container. From this, the required minimum design flow rate can be checked. It is the intention of NZS 4517 that this test should be witnessed by adequately trained plumbing inspectors, or other people acceptable to the BCA.

Summary

To ensure NZS 4517 fire sprinkler systems remain cost effective, sprinkler system certification, as required for commercial and industrial fire sprinkler systems, needs to be avoided. However, BCA inspectors need to familiarise themselves with NZS 4517 so they can recognise where NZS 4517 fire sprinkler systems are being installed outside the scope of the Standard. BCA inspectors need to ensure adequate commissioning tests for these systems have been performed and to ascertain the adequacy of the water supply when they see obvious signs, such as small water meters.

BCA inspectors also need to recognise that NZS 4517 fire sprinkler systems are cutting-edge fire prevention systems, with no latitude for error. A 'she'll be right' attitude will most certainly result in a NZS 4517 fire sprinkler system not performing when it activates to control a fire.