Introduction to Fire Safety Management

are used to prevent accidental discharge of water from
the sprinkler pipework following mechanical damage.
Domestic sprinklers – the vast majority of fi re
deaths and injuries happen in the home. Over the last
15 or so years the thrust for improving fi re safety in the
home has been centred around the provision of smoke
detection and although domestic smoke detectors do
save lives and are absolutely vital to reduce the risk of
death and injury in the home, it has recently become
obvious that early warning alone is not suffi cient to
reduce deaths in the home. The focus now for increasing
fi re safety in the home is moving towards the provision of
residential sprinklers.
Although a relatively new development in the UK
residential sprinklers are more common in America. In
one town in Arizona, all new homes have been required
to be fi tted with sprinklers for the last 15 years. As a
result, residential sprinklers now protect over 40% of the
dwellings in this town. A recent report showed that in the
past 15 years there has been:
➤ No fi re deaths
➤ 80% reduction of fi re injuries
➤ 80% reduction in property damage
➤ 95% reduction in water usage for fi re control.
In the UK domestic sprinkler systems should be designed
and fi tted to comply with BS 9251:2004: Sprinkler systems
for residential and domestic occupancies. These
must be designed in such a way that they are able to
cope with the expected size of fi re in the particular
building.
Drenchers
Drencher systems are installed to protect against radiated
heat or to fl ood a high risk process with water for
Water spray
Figure 9.63 The operation of a protective roof drencher system
Fire protection in buildings
guaranteed and rapid suppression. In essence a drencher
system is a range of pipework that resembles the range
pipes of a sprinkler system. Drenchers may be either
open or sealed. Open drenchers are operated simultaneously
by the opening of the main valve, while the sealed
type is individually actuated in the same way as a sprinkler
head. Sealed drenchers differ little from sprinkler
heads except in the shape of the defl ector plate.
While a sprinkler system protects a building from
internal fi re, drenchers are located on roofs and over
windows and external openings to protect the building
from damage by exposure to a fi re in adjacent premises.
The controlling valves for drencher systems are
located in accessible positions on or near ground level but
away from the adjacent fi re risk. The valves are secured
against unauthorised interference, protected from frost
and clearly indicated.
Drenchers normally operate on the alternate system,
and are more economical in the use of water than open
drenchers, since only those heads that operate are
required, and the pressure is maintained more effi ciently.
There are three main types of drencher system:
➤ Roof drenchers
➤ Wall or curtain drenchers
➤ Window drenchers.
Roof drenchers – roof drenchers have a defl ector
rather similar to that of a sprinkler head. From the
roof ridge they throw a curtain of water upwards which
then runs down the roof (Fig. 9.63). All parts of the roof
and any skylights, windows or other openings must be
protected.
Wall or curtain drenchers – wall or curtain drenchers
throw water to one side only of the outlet in the
form of a fl at curtain over those openings or portions
of a building most likely to admit fi re. A special use for
Roof pipework
Feed pipe supply
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