Types of Tanks Used to Store Water
Cylindrical Galvanised Steel or Aluminium Tanks
This type of water storage tank is the most common type used for sprinkler systems. Construction is of galvanized steel or aluminium sheets that are bolted together to form a cylinder. A mastic seal is applied between each metal sheet or a butyl rubber or EDPM liner is fitted. These tanks are usually installed close to the protected premises on a prepared concrete base or occasionally inside the protected premises.
Galvanised Pressed Steel Panel Tanks
These tanks are constructed using square steel panels that are bolted together to form a cube shape to suit the space available. They can be installed inside or outside the premises. This picture shows the access ladder, ball valve housing and tank infill pipe.
Profiled Galvanised Steel Panel Tanks
These tanks are constructed using square steel panels that are bolted together to form a cube shape to suit the space available. They can be installed inside or outside the premises.
Profiled Galvanised Steel Panel Tanks
The panels for this type of tank are curved and individually bolted to upright stanchions. They can be installed inside or outside the premises.
Moulded GRP Panel Tanks
These tanks are formed by bolting together square GRP panels to form a cube to suit the space available. They can be installed inside or outside the premises.
Corrugated Galvanized Steel Panel Tanks
The panels are bolted together to form a cube shape to suit the space available. They can be installed inside or outside the premises.
Can be any of the above tanks installed high up in a tall building, on a hill or on a separate high level platform. Depending on the tank’s elevation, the ‘static pressure’ or ‘head’ can sometimes be sufficient to supply the needs of the sprinkler system.
This is a cylindrical steel pressure vessel which is filled to two thirds capacity with water and one third with air under pressure. In the event of a fire the pressurised air expels the water and delivers it to the sprinkler system. This type of water supply can be found on older sprinkler installations and is no longer commonly installed on new sprinkler systems.
On sites where there is insufficient space above ground or because of planning restrictions an underground tank can be constructed from concrete. The standard for the construction of such tanks is BS 8007.
Retrofit Concrete Tanks
Where a concrete structure that will bear the load of the stored water exists on a site, it may be possible to provide a fire sprinkler water storage tank in a retro-fit situation. The concrete structure can be lined with a butyl rubber or EDPM internal membrane similar to that used in steel tanks. The lining material can be either pre-fabricated and taken to site in one piece and installed, or fabricated on site to suit a particular tank, through specialist hot vulcanising or welding techniques.
Single-piece GRP Underground Tanks
These are a single piece domed end cylindrical tanks which is installed below ground, strapped to a concrete base or with a concrete surround. At present, there are no tanks of this type listed by the LPCB.
Other Acceptable Sources of Water
Provided adequate capacity exists, swimming pools, lakes, canals and rivers can be used as the water source for a sprinkler system provided the supply and availability is guaranteed. Because these sources may contain foreign matter in suspension it is necessary to fit a strainer (and sometimes filters), to minimise the risk of clogging pumps and the sprinkler pipes.
Underground Tanks and Pump Houses
Underground tanks or pump houses may sometimes be the only option but these are subject to some constraints and problems may occur in respect of dampness as well as issues of access. It is strongly advised that the insurers views be sought before proceeding with such an installation. There is useful information on working in confined spaces in Part 3 (Supplementary Information) of the LPC Rules.