In compliance with the B.F.P.S.A. Code of Practice,
enclosures protected against fire by gas extinguishing systems
must be provided with a means of extracting the gas or post –
fire atmosphere to open air.
Independent, normally closed, mechanical ventilation with
extraction provides the most efficient solution and for
liquefiable gases with high boiling points, such as FM-200, the
room atmosphere should be vented from low level.
Ventpac self
contained system
As a means of complying with
this directive without the need to install a specialist
engineered system, GIELLE Fire Engineering are able to offer
the self contained VENTPAC extraction unit. Designed to suit
enclosure sizes up to 250m³ with or without voids, the
VENTPAC extract unit provides a minimum of four air changes
per hour.
Installation
simplicity
Simplicity of installation
is a major feature of VENTPAC. Contained within a Zintex
metal enclosure, the unit houses a high airflow centrifugal
fan and positive shutoff damper with motor and is very quiet
in operation. All components are electrically pre-wired to
the external terminal box for direct connection to remote
fireman’s switch or control facilities.
VENTPAC is complete with a telescopic transition duct,
requiring only a 250mm diameter aperture to be provided and
automatically allows for various external wall thickness
without the need for any specialist site fitting work. The
discharge duct terminates externally to a GIELLE got
connection fascia plate which is complete with a back
draught flap.
Dual path
extract
Room atmosphere is extracted
through the louvered grille, positioned in the end plate of
VENTPAC. Where floor void extraction only is required, a
quick release baseplate can be removed and interchanged with
the extract grille. For situations where simultaneous room
and floor void extraction are required, partial removal of
the baseplate allows dual enclosure extraction.
System
Specification
Pressure relief
requirements
Fixed fire extinguishing
systems employing inert gases extinguish fire by reducing
the oxygen content of the protected space. To achieve this,
a volume design concentration of 35% or more is normally
required.
Injection of this high concentration results in a positive
pressure, which displaces the atmospheric air from the room.
To compensate for this over – pressure, system
manufacturers generally specify that suitable venting should
be provided to alleviate any risk of structural damage.
Pressure relief
design
As part of the system design
programme, a calculation is made for the appropriate system
size, of the venting area required to prevent any damaging
over – pressurisation. System manufacturer tests and data
have established that normal build rooms will withstands an
increased pressure of 5mb (500 Pascals).
Any a means of complying with these requirements, GIELLE
Fire Engineering are able to offer the PRESPAC pressure
relief unit. Specially designed for use with fixed gas
extinguishing systems PRESPAC will open automatically when
the positive pressure reaches 1.5 mb (150 Pascals). As
pressure equalises the weighted relief blades close to seal
the enclosure and maintain the extinguishing concentration.
Fire rating
integrity
The BFPSA Code of Practice
stipulates that rigid elements of the protected enclosure
must have a fire resistance of not less than 30 minutes.
Often to comply with this directive it is necessary to
install a separate fire damper, in addition to the pressure
relief unit, which in the event of operation defeats the
object of fitting any over pressure device.
PRESPAC will maintain fire wall integrity without the need
to fit a separate damper. The unit has been independently
tested by Chiltern Fire to the general requirements of
BS478: Part 20: 1987, where it achieved over two hours
integrity.
Gielle Srl - Administrative Headsquares Via R. Ferri 32 Z.I. - 70022 Altamura (Ba) Italy
Tel +39 0803118998 - Fax + 39 0803101309
E-mail: info@gielle.it
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