Automatic sprinklers Design

Question 1

Label the layout of a

typical sprinkler system

Answer 1

1 Sprinkler heads
2 Hydraulic gong
3 Alarm gong drain
4 Waste and test valve
5 Pressure switch
6 Alarm valve
7 Main installation stop valve
8 Towns main stop valve
9 Towns main
10 Pressure tank

Question 2

Define the terms (a) ‘high rise’ and (b) ‘low rise’ systems

are used to describe systems where:

Answer 2

(a) The highest sprinkler is more than 45m
above the lowest sprinkler or the sprinkler
pumps, whichever is the lowest and;
(b) The highest sprinkler is not more than 45m
above ground level or the sprinkler pump.

Question 3

The BS/LPC Rules arranges occupancies into risk
categories each having an accepted abbreviation.
List the abbreviations

Answer 3

Category
Light Hazard    LH
Ordinary Hazard: Group I   OH1
Ordinary Hazard: Group II   OH2
Ordinary Hazard: Group III   OH3
Ordinary Hazard: Group IIIS (Special)   OH3 (S)
High Hazard  HH

Question 4

Define Light Hazard risk category of sprinkler and give 3 examples

Answer 4

These are non-industrial type premises of not more
than 126m2 between construction
not less than half-hour fire-resistance,
where the amount and combustibility of
the contents is low.
e.g. offices, libraries,
hospitals

Question 5

Define Ordinary Hazard group category of sprinklers

and give 3 examples from each group

Answer 5

commercial and industrial premises involving the handling, processing and storage of a very wide range of mainly combustible materials,
unlikely to burn intensely in the early stages of a fire.
It has been found necessary to sub-divide them into four groups as below:
Group I Breweries, dairies and restaurants
Group II Engineering works, garages, medium
size retail shops
Group III Soap factories, sugar refineries, aircraft
factories
Group IIIS Film and television studios, cotton
mills, match factories.

Question 6

Define high Hazard group of sprinklers

Answer 6

commercial and industrial premises having abnormal fire loads:
(i) Where materials handled or processed are
mainly of an extra hazardous nature likely to
develop rapid and intensely-burning fires.
(ii) Those involving high-piled storage.

According to the hazardous nature of the stock and
the height of the storage, those included in (ii)
above are sub-divided into four categories:

Category I Process high hazards
Category II High-piled storage hazards
Category III Portable spirit storage hazards
Category IV Oil and flammable liquids hazard

PH So ?

Question 7

What are the 3 classes of sprinkler system

Answer 7

(i) Light Hazard system
(ii) Ordinary Hazard system
(iii) High Hazard system.

Question 8

Each class of sprinkler system can be designed so pipework for two or more different types of hazard
system may be connected to a common set of control valves, provided the total number of sprinklers does not exceed the permitted maximum
true or false

Answer 8

true

Question 9

What is AMAO

Answer 9

Area of assumed max opertaion

Question 10

What is the minimum density ?

Answer 10

The amount of water required to control or extinguish
a fire
depends on Hazard class

Question 11

In what units is min design density measured

Answer 11

mm/min

Question 12

The minimum design density is a laid down standard for each class of sprinklers.
the standard is calculated using what criteria ?

Answer 12

1. Group of sprinklers ( usually 4 or more )
2. Most hydraulically remote from water supply
3. Part of a larger group of sprinklers discharging at the same time

Question 13

Define a Life safety system sprinkler

Answer 13

Basic sprinkler systems
enhanced to give a higher standard of reliability
and continuity of service.

Question 14

Life safety system sprinklers have what to ensure they are live during servicing ?

Answer 14

2 main valves one either side of the alarm valve.

Question 15

The ‘Life Safety’ requirements may include the

following:

Answer 15

(i) a wet type.
(ii) zoned, each zone being controlled by a separate stop valve and having a maximum of 200 heads.
(iii) A zone may require the installation control
valve-set to be duplicated so that one set of
valves can be serviced whilst the system is
operational.
(iv) No zone shall extend to an area of the building
under separate ownership.
(v) No zone shall extend to more than one floor
level but a zone may include a mezzanine
floor of not more 100m2.
(vi) Stop valves shall be accessible at the floor
level of the zone they control.
(vii) Only one zone of a multi-zone installation
shall be shut down at any one time. The fire
authority is to be advised of the intention and
should have to approve.
(viii) All stop valves and tamper-proof electrical
switches indicating that the valves are in the
correct operating mode shall monitor alarm
valves.
(ix) All practical steps shall be taken to ensure
continuity and reliability of water supplies.
(x) Means shall be provided to initiate visual
and audible warnings to an area with responsible
manning when the pressure in the
sprinkler trunk falls to the point at which the
pump should start. These warnings shall
‘latch in’ and only be capable of manual cancellation.
(xi) On indicator panels, audible alarms may be
silenced after the system has operated, but
the visual alarm signal shall remain until the
installation has been reset to its normal operational
position.