| Extinguishing gas: extraction unit |
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| Gas extraction requirements |
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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.
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| Ventpac self contained system |
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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.
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| Installation simplicity |
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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.
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| Dual path extract |
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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.
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| System Specification |
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| Pressure relief requirements |
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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.
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| Pressure relief design |
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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.
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| Fire rating integrity |
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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.
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Gielle Srl - Idari Ofis
Via R. Ferri 1001 - 70022 Altamura (Ba) Italy
Tel +39 0803118998 - Fax + 39 0803101309
E-mail: info@fm200.biz |
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