The Schoen Clinic in London is an award-winning private hospital specialising in orthopaedics and spinal care. Fireworks custom-designed and installed a watermist fire protection system to protect the different areas on all seven floors of this prestigious hospital.

Design specifications and fire hazard risks

The Schoen Clinic is an international group of private hospitals. Its specifications for the building in London included a high pressure watermist fire suppression system compliant with the design, installation, performance, commissioning and maintenance criteria for life safety in the BS8489 British safety standards.

Most of the hospital is designated an ordinary hazard risk level for fire (OH1). However, there are zones of higher fire hazard, such as the OH2 loading bay. There are several storage areas and no less than 9 plant rooms, identified as OH3 higher fire risk. A generator room on the ground floor was protected using watermist nozzles tested for machinery spaces. MRI rooms and void areas also needed to be protected.

System design

The watermist system installed high pressure pump units, a water tank and grade 316 stainless steel pipework connected to high pressure watermist nozzles.

The pump skid incorporates four + four pumps, doubled for life safety requirements. The pumps are fed directly fed from a water storage tank. Although flow tests undertaken confirmed a good supply of incoming water to the building, the design included a water tank sufficient for 60 minutes of fire suppression to conform with life safety requirements.

Different nozzles were selected for the various hazard areas. OH1 web-bulb systems were used for the general hospital areas. OH1 nozzles with dry pipe pre-action and solenoid valves were used for the MRI rooms. Loading bays were equipped with OH2 nozzles, while plant rooms were fitted with OH3 nozzles. In the event of fire, watermist will only be discharged through nozzles activated by heat from a fire, when the temperature reaches a pre-defined level. Special hazard HC1 nozzles were used for the generator rooms, with dual activation systems, triggered by flame and smoke detectors.

During servicing and maintenance, the watermist system will remain fully operational.

Testing and commissioning

In accordance with BS8489 the entire pipe work system was hydrostatically pressure tested to 1.5 times operating pressure of the system. Full function testing of the pumps was carried out and offered to client for witnessing, pre commissioning & commissioning.

Nozzles were tested and certified in accordance with FM5560 and VDS 3188 requirements.