Reliable sprinkler systems in the UK

In 1807, John Carey invented the first perforated sprinkler. This was connected to a pipe system which operated automatically when the heat of a fire burnt through a cord, which in turn held closed weighted valves. He had the right idea but the records remain silent of his success.

Possibly the oldest sprinkler installation in Britain was fitted in 1812 at the Theatre Royal Drury Lane and an updated form is still in use today.

In 1864, an Automatic Sprinkler Head, considered to be the forerunner of the present-day sprinkler, was introduced but never marketed. A significant breakthrough came in 1874, when an American named Henry Palmer Lee produced the first automatic sprinkler to be commercially marketed. The first English installation of the Palmer Lee System was erected in the Cotton Mills of John Stones & Co., Astley Bridge, Bolton.

Automatic sprinkler systems are used more than any other fixed fire protection system and over 40 million sprinkler heads are fitted worldwide each year. Losses from fires in buildings protected with sprinklers are estimated to be 1/10 of those in unprotected buildings.

In buildings fully protected by sprinklers:
99% of fires were controlled by sprinklers alone
60% of fires were controlled by the spray from no more than 4 sprinkler heads
Accidental discharge of water from all causes is 1 in 500,000 (per year of service)
Accidental discharge of water due to manufacturing defects is 1 in 14,000,000 (per year of service)

All communicating areas of the building should be protected and covered by an array of range pipes to which sprinkler heads are fitted at specific design intervals. Water from a water storage tank, a pump set or from the main’s supply (providing it meets the criteria for the risk) fills the sprinkler installation.

When it reaches a specific temperature, each sprinkler head will spray water onto the fire. The hot gases from a fire are usually enough to trigger water flow. Only the sprinkler head over the fire will operate and the others remain closed. This limits any water damage to areas where there is no fire and reduces the amount of water needed.

The sprinkler heads are generally spaced on the main roof or ceiling, so that if one or more operate there are always enough to control a fire, taking into account the size and construction of the building and its use. Sprinkler heads can be placed in enclosed roof spaces and into floor ducts to protect areas where a fire can start without being noticed. In a large warehouse, sprinklers may be placed in the storage racks as well as in the roof.

There are control valves on a sprinkler system which can be used to shut off the system for maintenance. For safety reasons, the main stop valve is padlocked open and only authorised persons should be able to close it. When a sprinkler head operates and water flows through the sprinkler alarm valve, it also sends water into another pipe that causes a water motor alarm bell to ring. In this way, the sprinkler system both controls the fire and gives an audible alarm using water.

In addition, a pressure switch which is connected to a fire alarm panel can be fitted to the installation control valves and sounds an audible alarm when triggered. This can also be connected via a telephone line to a central station and when operated without giving prior notice shall call out the local fire brigade.

WET PIPE

These are the most common type of installations and are used in buildings where there is no risk of freezing. They are fast to react because water is always in the pipes feeding the sprinkler heads.

‘Wet Pipe Installations’ are required for multi-storey or high-rise buildings and for life-saving purposes.

ALTERNATE

As the name suggests ‘Alternate Installations’ can have the pipes full of water in the summer months and be drained down and filled with compressed air for the winter months. This is important for buildings that are not heated as it prevents freezing of the pipes.

NB: Under the new BSEN 12845 Rules Technical Bulletin 232.4, Alternate Alarm Valves are no longer considered appropriate for Sprinkler Service, due to the potential for accelerating pipework corrosion. Existing Alternate Alarm Valves before the introduction of this rule may continue to operate and maintain in accordance with the standard.

DRY PIPE

The pipes are filled with compressed air and are under pressure at all times, and the water is held back by a different air valve. When a sprinkler head opens, the drop in air pressure opens the valve and water flows into the pipework and onto the fire. Dry pipe systems are used where wet or alternate systems cannot be used.

PRE-ACTION

Like dry pipe systems, the pipes are filled with air, but water is only let into the pipes when either a smoke or heat detector operates. Pre-action systems are used in Comms Rooms where it is not acceptable to have the pipes full of water unless there is a fire.

DELUGE AND RE-CYCLING INSTALLATIONS

These are not strictly sprinkler systems and are only used in special cases for individual risks.

Why are sprinklers important for fire safety?

In a large, fastmoving fire people often do not know which way to go and may not be able to use hose reels or fire extinguishers. Sprinklers are completely automatic. They work by themselves and can stop heat and smoke from trapping people.

How can we be sure sprinklers will work in a fire?

Most sprinkler systems are very simple. There are normally no moving parts to fail. The pipes are full of water, usually fed from the Towns Mains or a Pump & Tank. When the heads reach a set temperature of standard 68°C (155F), they spray water onto the fire.

What about water damage?

Reports of water damage from fires in buildings with sprinklers are often exaggerated. Only the sprinkler heads over a fire operate. All the others stay closed. A sprinkler opening by accident is almost unheard of. Firemen often use 10,000 times more water from hoses to do the same job as a sprinkler. A valuable item sprayed with water from a sprinkler as it puts out a fire can usually be recovered or restored. One that is burnt to a cinder and flushed down the drain by the fire hose is another matter! If there is a fire, the water from one or two sprinkler heads is a small price to pay for saving a complete building, its contents, or even a life.

We always request that our clients have adequate insurance cover in the event of water damage.

What about smoke?

Smoke damage is a major cause of loss in fires. In serious cases, smoke is the main cause of death. Sprinklers wash the larger particles out of smoke, reducing its density and toxicity. In addition, the water cools the smoke, making it less harmful. Quick response sprinkler heads will attack a fire even earlier in its growth; a faster attack will dramatically reduce the amount of smoke that a fire can produce.

What is the life safety record for sprinklers?

Apart from explosions, there have never been multiple fatalities in a fully sprinklered building in the United Kingdom. The total number of deaths worldwide in sprinklered buildings is only 50, compared to thousands in unprotected buildings. This is a record no other fire system can match.

Aren’t sprinklers unsightly?

Modern sprinklers are specially designed to meet the needs of architects in offices, hotels, shops, hospitals and prestige buildings. They are compact and elegant. In most buildings, the public are usually unaware that sprinklers are fitted.

Miniature sprinklers are little bigger than a 50p piece and are neat and robust. They can be fitted with ceiling rosettes and supplied painted to any colour scheme.

Concealed sprinklers are recessed and covered by a flat plate flush with the ceiling. They are unobtrusive and almost invisible. Concealed sprinklers are ideal for clean areas, where there is restricted headroom or vandalism is a problem.

The Benefits of Automatic Fire Sprinkler Systems

Fire sprinklers:

• Save lives

• Reduce the risk of death

• If activated reduce property damage

• Are relatively inexpensive

• Typically reduce insurance premiums

• Are virtually maintenance free

• A Commercial Investment

A sprinkler system is a first-class investment, returning a fair interest in insurance discounts long after the initial outlay has been recovered. Depreciation is reliable, as indeed it must be for equipment designed to remain unused for many years and then called upon to act in an emergency.

Installations erected over half a century ago still qualify for insurance discounts, and evidence of fires extinguished proves that they would be instantly effective today.

It must be remembered that sprinkler installations are considered as a plant by the Inland Revenue and qualify for investment, initial and depreciation allowances currently in force. But perhaps their greatest investment value lies in the fact that they are in themselves an insurance policy designed to provide safety to life and continuity of business. No other form of fire protection can prevent a major fire, which would otherwise cause a loss of value from customers being forced to place their business elsewhere.