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 kilometers
apart;
- be based on an open protocol;
- 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.
System specification
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.
Conclusion
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."