The LWF Blog

Fire Safety for Facilities Management Personnel – Sprinkler System Components – Part 232

December 18, 2023 12:08 pm

Lawrence Webster Forrest (LWF) is a specialist fire engineering and fire risk management consultancy whose aim is to give information on best practice in fire safety for facilities management personnel through this blog series. In part 231, LWF looked at the design codes for sprinkler systems. In part 232, we begin to examine the components of a sprinkler installation.

The basic components of a sprinkler installation are:

• A water supply
• A main valve set
• A network of pipes
• A number of sprinkler heads

Other key elements you would see on a design for a sprinkler system are:

• Main stop valve
• Wet alarm valve
• Remote alarm pressure switch
• Alarm gong isolating cock
• Drip plug
• Alarm line strainer
• Water motor & alarm gong
• Alarm line drain tundish
• Alarm test valve
• System drain & test valve
• Flow meter
• ‘B’ Pressure gauge
• ‘C’ Pressure gauge
• Test cock

Each sprinkler head is a combined heat detector and discharge valve. When the temperature sensing detection element reaches a certain temperature, the valve opens and water is discharged.

Each sprinkler head operates separately from the rest (except in the case of deluge systems, where a group of heads open at the same time). A fire may be controlled or extinguished completely by the operation of just a few sprinkler heads and the popular image of all sprinkler system heads operating simultaneously (as often seen on TV) is incorrect. If all sprinkler heads did operate simultaneously, the potential for water damage throughout a building would be significant, aside from it being unnecessary for the purpose of the installation.

Sprinkler pipework is usually permanently charged with water which is immediately available as soon as the first sprinkler head opens. These are permanently ‘wet’ systems. In unheated buildings, such as warehouses, alternative systems may be necessary. It may be that during the Summer months, the system is permanently ‘wet’ but in Winter, where the water contained in the pipework may freeze, it is drained and charged with air, becoming ‘Dry’.

For systems that can be ‘wet’ in Summer and ‘dry’ in Winter, a special alternate valve set is required, which allows water to enter the installation pipework when the air pressure is lowered by the operation of the sprinkler head(s). In some circumstances, such as in cold storage, permanently ‘dry’ systems may be required.

 

In part 233 of this series, LWF will continue to discuss sprinkler system installations and components. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact LWF on freephone 0800 410 1130.

Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 35 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.

 

While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.