Technical Fire Sprinkler FAQ’s
Some of the more common technical questions:
1. Does the Property Require a Full or Partial Domestic Fire Sprinkler Suppression System?
Most houses are defined as ‘category one’ in which case except for restrooms under 5m2 and cupboards with a floor surface of less than 2m2, BS 9251 requires sprinkler protection in all portions of the structure (with a few minor exceptions). However, the BCO routinely grants exceptions to this rule. Because these BS 9251 relaxations are at the discretion of the BCO, we are unable to provide anything more than basic guidance based on facts. As a result, it is critical to find out what level of protection is necessary from the BCO as soon as feasible and for properties that have been graded ‘category 2 to 4’ advise should be sought from the system designer. The RAD technical department can provide this advice.
2. What Type of Water Supply Will be Required?
The policies of water companies regarding domestic and residential fire sprinkler supply vary greatly, and our knowledge in this area allows us to provide recommendations based on current trends. However, due to the high flow rates required by conventional sprinkler systems, it is unusual to be able to adapt an existing water supply into a conventional retrofit household fire sprinkler system. In most cases, the decision is between a new water supply and a storage system. However, High-Pressure Mist systems are designed to be fed by a standard 22mm domestic supply.
The cost of a fire sprinkler storage system is frequently less than the cost and disturbance of delivering a new supply for a retrofit installation. Most household fire sprinkler systems for new build properties can be run straight from the town mains supply if the provision is made early enough in the construction phase.
3. Why Can’t A Conventional Sprinkler System be Fed from Our Existing Mains Water Supply?
A fire sprinkler system requires a large amount of water with a specified level of pressure behind it, known as dynamic pressure. A standard mains stopcock is intended to control the flow of water in the event of a sudden demand, such as a burst water pipe. When this feature of a standard household supply is combined with a domestic metre that likewise restricts big flows of water, it follows that a standard domestic water supply is unlikely to be suitable for a fire sprinkler system unless it was built for this purpose when the supply was installed. The best solution, in this case, is to utilise a High Pressure Mist system.
4. At What Point Do I Instruct a Fire Sprinkler Contractor?
As early in the build as possible because the sprinkler system design must be submitted to the Building Control Officer for approval, we encourage our customers to seek written confirmation of any variations from British Standard BS9251 for approval by the BCO. In general, the fire sprinkler installation firm chooses to start its first fix before other trades proceed with their 1 fix process.
5. At What Point in the Build Does the Fire Sprinkler Installation Start?
The installation method is similar to that of plumbing or electrical work. There are three stages: first fix, second fix, and commissioning. Because of the high flow rates associated with household fire sprinkler systems, pipework can be slightly bigger than standard plumbing pipe sizes, and an American 'fire-resistant plastic' system is often used in the UK instead of 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 approximately 1200 litres of water weighing approximately 1.2 tonnes of water. If tanks are installed in the loft, coffin water tanks can be used to distribute the load across multiple joists. These tanks frequently fit fairly comfortably between the rafters and the ashlar walls.
7. Is the Pipework Flexible?
Pipework in conventional domestic and residential fire sprinkler systems typically comprises of flame-resistant cpvc which has limited flexibility although more flexible than copper pipework. High pressure Mist systems, however, utilise pre-engineered hoses which have the advantage of being extremely flexible making these systems very suitable for retrofitting.
8. How Big is the Pipework and Can it be Concealed?
The external diameter of most flameproof cpvc pipework in domestic premises is either 28mm or 35mm. The way up through a house is frequently identical to the route of the soil stack. When the pipework runs perpendicular to the joists, the joists will be drilled on the centre line between 0.25 and 0.4 of the joist span. Another advantage of installing a High Pressure Mist System is that the holes are considerably smaller – generally less than 25mm in diameter.
9. Will all of the Sprinklers or Mist Nozzles Go Off at Once?
No, each sprinkler or Mist Nozzle is a self-contained heat detector that will only activate when a certain temperature is reached. In the event of a fire, only the heads in immediate proximity will operate, rather than the entire building.
10. How Do Sprinkler Heads Work?
A sprinkler head is a temperature-controlled valve that opens to spray water when a heat-sensitive element reaches a certain temperature. A temperature of 68°C or 74°C well enough under normal conditions in temperate climates. When needed, sprinkler heads with an operating temperature range of 57°C to 230°C are available.
11. Can systems installed to BS 9251 or BS8458 be Used in Car Parks?
No, BS 9251 and BS8458 is exclusively intended for use in residential and domestic settings. A parking park's more acute hazard necessitates a larger application of water via an increased design density/volume of water discharged. This system should be constructed following BS EN 12845: 2009.
12. Will the System need to be Maintained?
Most modern sprinkler or mist systems require relatively little maintenance to function properly all year. Systems are typically checked twice a year to ensure that they are running properly. Checking the pumps manually on a weekly or monthly basis will assist to maintain and extend the life of your system.
13. Do Sprinklers Create More Damage than the Fire Brigade would?
Most conventional sprinkler heads will discharge between 40 and 120 litres of water per minute, depending on the type of system. Sprinklers will turn on when a specified temperature is reached. No fire department in the country can respond as quickly as a sprinkler system. Firefighters typically pump 1000-3000 litres of water per minute into a structure. This indicates that automatic fire suppression devices are less likely to cause harm than a fire department.
The water quantity usage is considerably reduced further by utilising a High Pressure Mist System which does not use more than 12 litres of water per minute.