Some of the more common technical questions:
1.Does the property require a full or partial domestic fire sprinkler suppression system?
BS 9251 states that (other than some small exceptions) sprinkler protection should be provided in all parts of the building except bathrooms below 5m² and cupboards with a floor area less than 2m². However, relaxations to this are frequently granted by the BCO. Because these relaxations to BS 9251 are at the discretion of the BCO it is difficult for us to offer anything more than general advise based on empirical evidence. It is therefore very important to find out what level of protection is required from the BCO as early as possible.
2. What type of water supply will be required?
Water company’s policies on domestic and residential fire sprinkler supplies vary considerably and our experience in this matter enables us to provide advice based on current trends. As a rule of thumb however, it is unusual to be able to incorporate an existing water supply into a retro-fit domestic fire sprinkler system because of the high flow rates that these systems require. Generally, the choice is between a new water supply and a storage system. The cost of a fire sprinkler storage system often compares favourably with the cost and disruption involved in providing a new supply for a retrofit installation. Most domestic fire sprinkler systems for new build properties can be run direct from the town mains supply providing that provision has been made sufficiently early in the build process.
3. Why can’t the sprinkler system be fed from our existing mains water supply?
A fire sprinkler system requires a large quantity of water with a certain amount of pressure behind it referred to as dynamic pressure. A normal mains stop cock is designed to restrict the flow of water when there is a sudden demand like a burst water pipe. When this feature of a normal domestic supply is combined with a domestic meter which also restricts large flows of water it follows that a normal domestic water supply will most likely be unsuitable for a fire sprinkler system unless it had been designed for this purpose when the supply was installed
4. At what point do I instruct a Fire Sprinkler contractor?
The sprinkler system design will need to be submitted to the Building Control Officer prior to the installation and we advise our customers to obtain confirmation in writing to any deviations to the British Standard BS9251 that have been granted by the BCO. Generally, the fire sprinkler installation company prefers to commence their 1st fix before any other trades.
5. At what point in the build does the Fire Sprinkler Installation start?
The installation follows the same process as any plumbing or electrical work. There is a first fix, a second fix and a commissioning stage. Because of the high flow rates associated with domestic fire sprinkler systems, the pipe work can be marginally larger than normal plumbing pipe sizes and an American ‘fire proof plastic’ system is widely used throughout the UK in preference to copper.
6. For a storage system: how much water do I need to store and what do the water tanks weigh?
Most domestic systems require around 1000 litres weighing around 1 tonne. If tanks are placed in the loft, coffin water tanks can be utilised which spread the load over a number of joists. These tanks often fit quite comfortably in the space created between rafters and ashlar walls.
7. Is the pipework flexible?
The pipe work used in Domestic and Residential fire sprinkler systems is normally a flame proof cpvc system. Although this is marginally more flexible than copper, straight runs are
8. How big is the pipework and can it be concealed?
Most flame proof cpvc pipe work in domestic premises has an external diameter of either 28mm or 35mm. Often the route up through a house is similar to the route of the soil stack. When the pipe work runs at right angles to joists the joists themselves will be drilled on the centre line in a position between 0.25 and 0.4 of the joist span.
8. Will all of the sprinklers go off at once?
No, each sprinkler is a self contained heat detector that will only operate once a predetermined temperature has been achieved. This means only the heads in the immediate vicinity will operate in the event of a fire and not the whole building.
9. How do sprinkler heads work?
A sprinkler head is a temperature-controlled valve that opens, to release a spray of water, when the heat-sensitive element reaches a specific temperature. Under normal conditions in temperate climates, a rating of 68°C or 74°C will be suitable. However, sprinkler heads with an operating temperature range from 57°C to 230°C are available when required.
10. Can the BS 9251 be used in car parks?
No, BS 9251 is intended only for use in residential and domestic premises. The more serious hazard of a car park requires a greater application of water through an increased design density/volume of water discharged. This system should be designed to be BS EN 12845: 2009.
11. Will the sprinkler system need to be maintained?
Most modern sprinkler systems require very little maintenance to keep them running smoothly all year around. Systems are usually check twice a year to make sure they are functioning as they should be. Checking the pumps on a weekly or monthly basis yourself will help to maintain and improve the longevity of your system.
12. Do sprinklers create more damage the fire brigade would?
Most sprinkler heads will discharge around 35 to 100 litres of water per minute; however, this depends on the type of system. Sprinklers will activate once a certain temperature has been achieved. No fire brigade in the country can act as quickly as a sprinkler system can. Fire crews will usually pump around 1000-3000 litres of water per minutes into a property. This means that automatic fire suppression systems are likely to cause less damage than the fire brigade would.