When you ask your fire engineer this question, the short answer generally is:
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You may have read in one of our previous blog posts that the National Construction Code 2019 Amendment 1 (NCC) permits the use of dry hydrant risers in certain Class 2/3 buildings when protected with automatic fire sprinkler systems.
So what is a dry fire hydrant riser and why is it such a hot topic in the fire industry right now? We’re here to break down the history and provide context on its perception in the Adelaide fire industry.
What is a Dry Fire Hydrant Riser?
Let’s take a step back. What are fire hydrant risers? They’re water-charged pipes that run vertically within fire isolated stairways and provide a pressurised water supply to the fire brigade for firefighting on multi-storey buildings. The relevant Australian Standard which governs the design and performance of these systems is AS2419.1.
Dry fire hydrant risers, as the name suggests, are risers which do not contain any water and for all intents and purposes, are generally disconnected from the building‘s fire water supply. They’re effectively a dry piece of vertical pipe which gets flooded by the fire brigade when they arrive on site.
The design principle behind dry hydrant risers is that the water is only added when the fire brigade need it and skirts around issues relating to insufficient water pressure at upper floors of the building.
The Stigma
Unfortunately, there are several drawbacks to a dry fire hydrant system which are documented in numerous documents mentioned later in this piece.
To summarize them:
No means to prevent foreign objects from being placed in the pipework and posing a significant safety hazard when the system is eventually charged with water.
Often no air release valves to purge air from system (avoiding pressure surges)
No capability to undertake initial firefighting prior to fire brigade boosting.
Longer set up time when compared to a wet fire hydrant system (having to check all hydrant valves are closed, finding a suitable water supply, purging system).
Increased risk of corrosion within the pipework due to the presence of air.
Lack of clarity on maintaining the water supply at an acceptable level as it doesn't strictly connect to the system.
The Grenfell Tower fire in the UK in 2017 did not help boost (excuse the pun!) the image of a dry hydrant riser system as post-incident investigations indicated this was a major concern for the responding fire brigade.
South Australian Stance
The South Australian Metropolitan Fire Service (SAMFS) released a guideline document to outline their position on the use of dry fire hydrant risers. They outline several times in this document that they do not prefer the use of this system operationally due to several of the reasons mentioned above.
Similarly, the Australasian Fire Authorities Council (AFAC) released a guidance document relating to the design and installation of dry fire hydrant systems which strongly recommends the use of wet fire hydrant risers complying with AS2419.1.
This makes for a bit of an awkward situation as fire authorities across the country have expressed their distaste for these systems but the Deemed to Satisfy (DtS) provisions of the NCC permit it to be installed.
Whilst this is true, the moment you have Performance Solutions applicable to your building which requires fire brigade consultation, one of the first items which may be requested is, you guessed it, a wet fire hydrant riser.
Can it be Used?
So I know what some of you are thinking: If we go down the path of a DtS building design which doesn’t require fire brigade consultation, we’ll get away with a dry hydrant system right? Not exactly.
The fire brigade still need to commission the system one it’s installed regardless of whether it’s DtS or has Performance Solutions. If they’re dissatisfied with its configuration or installation arrangement, they could necessitate additional works to be completed on it such as charging it with a water supply.
On top of that, there is a small section in the NCC which gives the fire brigade power to request specific fire protection provisions if they deem the building to be of “special hazard”. While it could be a stretch to say that a 3-storey apartment building is a special hazard, it leaves room for interpretation by the authorities.
Conclusion
At the end of the day, SAMFS are advocating for wet fire hydrant risers in lieu of dry because it is operationally a better system and it removes unnecessary tasks which allow the fire brigade to concentrate more on search and rescue and asset protection operations.
Long story short: a wet fire hydrant system could one day be the difference in saving an additional life when compared to a dry hydrant system.
Notwithstanding the above, of course we can design your dry hydrant system and handle consultations with the fire brigade. Just contact us to learn how.
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