FIRE SPRINKLER SYSTEM

Sprinklers operate by responding to heat. Sprinkler heads come in a wide range of activation temperatures, from 57°C to 260°C – the sprinkler system designer will select a head temperature that is appropriate to the risk/area (but that should never be less than 30°C more than the operating ambient temperature of the area to help prevent false discharges). 

As detailed above, when the frangible elements in the sprinkler head reaches its operating temperature it will break –, thus opening the head and allowing water to flow through the nozzle and onto the fire. 

and onto the fire. 

If the sprinkler system is supplied via a pump and tank system, the drop in system pressure caused by the flow of water through the activated sprinkler head will cause the pumps to start.   

At the same time, flow switches on the sprinkler system will be used to activate the fire alarm for an evacuation signal and any associated notifications or actions. 

Fire sprinkler systems are incredibly effective in controlling and often extinguishing fires before they can spread. Studies have shown that the chances of dying in a fire in buildings with operational sprinkler systems are reduced by 81% compared to buildings without them. Sprinkler systems also reduce property damage by 70%. 

Yes, fire sprinkler systems can and often should be integrated with other fire protection systems, like fire alarms and smoke detectors. This integration can increase the overall safety and efficiency of the building’s fire defense mechanisms, providing early warning and allowing the correct follow-up actions, such as calling the fire and rescue service, shutting down your process and other measures. 

Although rare, fire sprinklers can accidentally discharge due to mechanical failure or inadvertent activation, leading to significant water damage. This is a particular concern in spaces with sensitive equipment or valuable items.  

In these high-operational impact scenarios (i.e., data room floors for cable protection), it is common to use an ‘interlocked pre-action system‘, whereby it requires the activation of a separate fire detection system to release water into the sprinkler pipes – plus the activation of a sprinkler head to allow that water to flow from the system.  This method overcomes the risk of a false discharge. 

Sprinkler systems respond to heat, which means there can be a delay between the start of a fire and the heat having built sufficiently to activate the sprinkler head(s). This delay can let the fire grow into a fast-moving fire before the sprinklers activate. However, this concern is often offset by the fact that suppression follows very swiftly after activation of a sprinkler head, so the fire growth is quickly controlled. 

Ensuring a reliable and sufficient water supply can be a challenge, specifically in areas with limited water availability or pressure. This might require the installation of pumps or reservoirs, further increasing the cost. 

In environments where you have a high ceiling in a storage building, there is justifiable concern by building operators that by the time a sprinkler head activates, there will be a substantial fire raging below.  For example, this is a common cause for concern in waste recycling facilities. 

There is good reason for this concern – a standard rule of thumb is that a fire can double in size every 30 seconds.  Clearly, different hazards and fuel types will have a different fire growth rate, but irrespective the principle is the same – let the fire develop for too long and it will be raging out of control before your sprinklers intervene. 

This question is too broad to provide a proper answer here, but there are a number of points that should be considered in high roofed buildings with sprinkler protection: 

• What is the fuel source?  How quickly will a fire grow? 
• How close does the fuel source come to the roof?  For example, rack storage all the way to the roof is a very different storage scenario to having low-piled storage of combustible plastic or mixed waste. 
• What sprinkler testing data has been conducted on your type of storage application?  There is lots of great test data conducted by the likes of FM Global for various industrial and storage applications. 
• Do you need to have additional ‘primary’ firefighting systems such as water cannons or deluge to protect the area (activated by fast response flame detectors or similar measures), with your sprinklers providing secondary protection of the building and structure?  Our Fire Rover automatic water cannon system is ideal for these applications. 

As a general rule, if you have a solid obstruction over 1m wide you need sprinkler protection below that point, as well as at roof level.  Typical examples of this could include below conveyors or machinery.  These are sometimes called ‘shielded area’ sprinklers. 

This is to prevent the machinery from creating an ‘umbrella’, below which a fire can develop whilst shielded from the roof sprinkler above. 

Almost invariably, the answer will be YES.   

In the UK, there isn’t sufficient flow and pressure in the public water mains to effectively operate a fire sprinkler system – this means you will need to install a ‘pumped water supply’ to provide the water demands of your sprinkler system. 

A sprinkler pumped water supply will require the use of a water storage tank, one or more sprinkler fire pumps, plus a ‘jockey pump’ which is used to maintain the pressure in the sprinkler system.  

A sprinkler valveset is a device which controls and monitors the flow of water to the sprinkler heads on that ‘installation area’. A sprinkler system can be made up of multiple ‘installation areas’, covering different parts of the building/process. 

So, in short, the valveset sits between the pumped water supply and the sprinkler head.  If a sprinkler head on that ‘installation’ activates, the flow of water is detected from the valveset, allowing accurate identification of the zone area in which the sprinkler activation has occurred.  The valveset includes the isolation and drainage valves which are used to reset the system after an activation. 

There are different types of valveset for the different types of sprinkler system. 

As detailed below, there are different types of valveset for the different types of sprinkler system.  

There are three main types of fire sprinkler systems – Wet, Dry, and Pre-Action.  There are also some legacy ‘Alternate’ systems still in use.  These systems are   

• Wet Sprinkler Systems are the simplest.  All of the pipework between the sprinkler pumps and the sprinkler head is constantly filled with water.  This ensures the fastest possible activation speed of the sprinkler head.  However, in areas where there is a risk of freezing, wet sprinklers would require full trace heating and lagging – which is both costly and can cause longer term maintenance challenges. 

• Dry Sprinkler Systems utilise air (or nitrogen) filled pipework between the ‘sprinkler valveset’ and the sprinkler heads, via a compressor installed at the valveset which pressurises the pipework and keeps the valveset ‘closed’.  This prevents the risk of frost damage to the roof mounted sprinkler pipework/heads.  In the event of a sprinkler head being activated, the air pressure stored in the pipework will escape from the opened head.  This pressure drop allows the valveset to open and water will flow through the pipework and out of the open sprinkler head(s).   The entire system area will need to be fully drained when resetting the sprinkler system.  

• Alternate Sprinker Systems are a combination of wet and dry valvesets.  During the summer months, the pipework will be kept wet to allow for a faster activation speed.  During the winter months, the pipework will be kept dry for frost protection.  

• Pre-Action Sprinkler Systems utilise a separate fire detection system.  If the fire detection system is activated, this will trigger the pre-action valve to open, filling the pipework with water in readiness for a sprinkler head activating.  These systems will sometimes be combined with activation upon pressure drop in case of the detection system not being properly activated.