Electric Mountain
It isn't every day you need to specify a fire detection system for an industrial complex inside a mountain - but that was the challenge facing International Power, owners of Dinorwig Power Station near Snowdonia National Park in North Wales.
Built in 1984, Dinorwig hydro electric power station offers one of the fastest response times of any power facility in the world, generating 1,728MW from standstill in just 90 seconds. Virtually all the critical plant at Dinorwig is situated underground. Some of the main areas requiring fire protection are also on a massive scale: the machine hall, for example, is 180 metres long, 23 metres wide and 51 metres high.
International Power developed a specification that would deliver a networked fire detection system to cover overground and underground areas of the power station sited several kilometres apart; be based on an open protocol and include aspirating fire detection.
Working in partnership, Apollo Fire Detectors Limited and Kentec Electronics Limited were able to demonstrate that a fire detection system based on Apollo's open digital protocol would fulfil International Power's unique requirements.
The new Dinorwig fire detection system is based around 12 Kentec Syncro analogue addressable control panels - eight of which are installed underground. Three graphic panels based on Kentec's GUIDE system provide a single point of co-ordination for all alarms and are positioned in the pressurised main control room underground, the administrative offices, and at the main gatehouse.
More than 1500 Apollo XP95 fire detectors and ancillary devices are incorporated in the new fire system. Optical smoke detectors are used in the main areas and approach tunnels, with heat detectors protecting rest rooms and kitchens. In excess of 450 addressable sounders and sounder beacons alert staff to an emergency and around 250 manual call points enable employees to raise an alarm.
An aspirating system has been fitted in the main cavern so that air turbulence will not affect the system's ability to detect fire. Water spray and gas extinguishing systems are also installed in the transformer rooms at the power plant. Approximately 100 Apollo interfaces enable this equipment to link in to the main fire detection system.
Andrew Taylor of International Power comments: "We were able to use standard fire detectors from Apollo's range to achieve the reliability levels we required in our subterranean environment. This helped to control costs and timescales on the project.
"The inclusion of aspirating fire detection could have been an issue, but the choice of an open digital protocol, plus the existence of an Apollo interface to link this in, avoided any compatibility problems."
Although the power station is highly complex in its fire detection requirements, the evacuation principle is simple: one alarm, all out - except a few essential staff in the control room.
In addition to International Power staff, the site is subject to regular tours for the general public so evacuation procedures needed to accommodate people who are unfamiliar with the site layout. The new fire system meets modern standards by providing reliable noise dispersal, with loop powered sounders and sounder beacons in the machine hall where noise levels may prevent audible alarms being heard.
The fire detection system at Dinorwig now offers comprehensive coverage across the entire site. Thanks to Apollo's open digital protocol, the point fire detection, aspirating detection and extinguishing systems are fully integrated. Kentec's sophisticated graphics controls provide a user friendly interface that enables routine maintenance issues and sources of alarms to be pinpointed and responded to effectively.
Andrew Taylor concludes: "The new fire system certainly gives us peace of mind that Dinorwig power station is protected from fire hazards and that we can get everyone out should an incident arise."
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