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ENCLOSURE REQUIREMENTS
The enclosure
should be of fire resisting construction, able to withstand the
ingress of fire from outside, and of sufficient strength to
retain the agent. PYROSHIELD displaces air in the enclosure and
it is necessary to provide venting, which allows excess pressure
relief during discharge, normally at a fairly high level in the
enclosure wall. The one-way vents close at the end of the
discharge, enabling the concentration to be held. In the UK,
room strength is generally taken as 500 Pascal, and, for
internal stud walling, 250 Pascal is taken. The venting formula
in our design calculation suggests the appropriate vent area.
Once the design
concentration has been achieved, standards require that it be
held for not less than ten minutes, or other agreed period.
Although PYROSHIELD will leak more slowly from a given enclosure
than the halocarbon agents, a room integrity pressure test is
still required, and leakage paths sealed if necessary. The
integrity test method is detailed in the British Standard, for
Gaseous Fire Fighting Systems ISO 14520.
SYSTEM REQUIREMENTS
All systems are
designed within the requirements of ISO 14520, or more closely
defined requirements where found in appropriate national and
international standards.
Each system is
carefully tailored to the risk to be protected. A risk
assessment is the starting point for the protection. Is an
PYROSHIELD system the best way to protect the risk? If so, is
the enclosure adequate to contain the gas, or can it be made to
be adequate? What materials are likely to be involved in a fire,
and which require the highest concentration for extinction? What
is the volume of the enclosure; is it connected to other
volumes? What is the actual volume to be protected? What is the
best type of detection to give early warning but minimum
possibility of false alarms? Will people be present in the
enclosure at a time when a fire could occur? Where is the best
place to locate the system cylinders - with regard to system
design, location to the fire, ease of maintenance?
Given the answers
to these questions, a system can be designed, determining the
quantity of gas required the location of detectors, nozzles and
distribution pipes, interlocks for doors, vents, air
conditioning etc. Using well proven software, the sizes of pipes
and nozzles can be readily determined, and the system designed
in accordance with the appropriate standards.
SYSTEM MAINTENANCE
PYROSHIELD fire
extinguishing systems are protecting life, facilities and
sensitive equipment, and it is of paramount importance that they
retain their capabilities 24 hours a day, 365 days a year. The
high quality of the system components employed goes some way
towards achieving this, our engineers fully maintain systems to
specification, and also re-examine the risk and check the
enclosure to ensure that, if changes have been made, the leakage
rates will still be within the limits for effective fire control
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