Hazard identification and classification of a premises, is usually carried out by the Insurer or Fire Authority and provides the basis for the design of the sprinkler system.

The hazard classification affects the choice of installation, operational method, water supply arrangements and pipework design.

The majority of retail units within shopping centres have a hazard classification of Ordinary Hazard Group III (OHG III).
Within OHG III, there are sub-categories of Property Protection and Life Safety.

OHG III Life Safety hazard classification’s primary function is to save lives by only controlling the fire long enough for the occupants to escape or be rescued.

OHG III Property Protection hazard classification’s primary function is to save the loss of buildings and contents. These systems are designed to control the fire until the fire brigade can extinguish the fire, thus saving the majority of the property and contents.

Property protection systems utlilise standard response type sprinkler heads and life safety systems use fast respose type sprinkler head.

Tenant's handbooks are usually issued from the shopping centre/property developer prior to works starting on site. Within the handbook, the hazard classification will be indicated, as will various other procedures that also need to be adhered to.

Every retail unit within a landlord's system must have a sprinkler isolation valve and flow switch. The isolation valve is usually the responsibility of the landlord, with the flow switch usually being the responsibility of the tenant.

The flow switch is electrically monitored to either the local fire alarm panel or direct to the shopping centre's central monitoring station. When a sprinkler head operates, the flow of water through the head/pipe will be detected by the flow switch and, in turn, send the local fire alarm system into evacuate. As well as the tenant's fire alarm penal sounding, the entire shopping centre shall go into full evacuation mode.

The isolation valve enables each unit to be isolated individually. When the isolation valve is closed, the individual retail unit can be drained and modified without interfering with the landlord's system.

Isolation valves are electrically monitored to either the tenant's fire alarm panel or direct to the landlord's central monitoring system. This monitoring ensures that unauthorised tampering with the live system will be detected and rectified. (Retail units cannot be isolated without permission.)

On operating the keyswitch, the pump will circulate water around the flow switch, simulating the action of a sprinkler head operating. This will send a signal back to the fire alarm panel. The landlord must be aware of this test prior to commencement to avoid evacuating the centre unnecessarily.

For more information on the requirements for retail unit sprinkler systems call us on
01769 574070 or email fds@fire-defence.com