Life Safety and Fire Fighting Systems – The weakest link

Unlike other cables, fireplace resistant cables have to work even when immediately uncovered to the hearth to keep essential Life Safety and Fire Fighting tools working: Fire alarms, Emergency Lighting, Emergency Communication, Fire Sprinkler pumps, Fireman’s Lift sub-main, Smoke extraction followers, Smoke dampers, Stair pressurization fans, Emergency Generator circuits etc.
In order to categorise electrical cables as fire resistant they are required to endure testing and certification. Perhaps the first frequent fire tests on cables were IEC 331: 1970 and later BS6387:1983 which adopted a gas ribbon burner check to provide a flame in which cables were placed.
Since the revision of BS6387 in 1994 there have been 11 enhancements, revisions or new check standards launched by British Standards for use and software of Fire Resistant cables however none of these seem to address the core issue that fireside resistant cables the place tested to common British and IEC flame test requirements usually are not required to perform to the identical hearth efficiency time-temperature profiles as each other construction, system or component in a constructing. Specifically, the place fire resistant buildings, methods, partitions, fire doorways, hearth penetrations fireplace obstacles, floors, partitions and so on. are required to be fireplace rated by constructing laws, they are tested to the Standard Time Temperature protocol of BS476 parts 20 to 23 (also generally known as ISO834-1, ASNZS1530pt4, EN1363-1 and in America and Canada ASTM E119-75).
These checks are carried out in large furnaces to copy real publish flashover fire environments. Interestingly, Fire Resistant cable test requirements like BS 6387CWZ, SS299, IEC 60331 BS8343-1 and 2, BS8491 only require cables to be uncovered to a flame in air and to decrease ultimate take a look at temperatures (than required by BS476 pts 20 to 23). Given Fire Resistant cables are likely to be uncovered in the same fire, and are needed to ensure all Life Safety and Fire Fighting systems stay operational, this truth is probably shocking.
Contrastingly in Germany, Belgium, Australia, New Zealand, USA and Canada Fire Resistant cable techniques are required to be tested to the identical fireplace Time Temperature protocol as all different building elements and this is the Standard Time Temperature protocol to BS476pts 20-23, IS0 834-1, EN1363-1 or ASTM E119-75 in USA.
The committees creating the standard drew on the guidance given from the International Fire Prevention Congress held in London in July 1903 and the measurements of furnace temperatures made in many fire tests carried out within the UK, Germany and the United States. The checks have been described in a series of “Red Books” issued by the British Fire Prevention Committee after 1903 as nicely as those from the German Royal Technical Research Laboratory. The finalization of the ASTM normal was closely influenced by Professor I.H. Woolson, a Consulting Engineer of the USA National Board of Fire Underwriters and Chairman of the NFPA committee in Fire Resistive Construction who had carried out many checks at Columbia University and Underwriters Laboratories in Chicago. The small time temperature differences between the International ISO 834-1 take a look at as we all know it today and the America ASTM E119 / NFPA 251 checks likely stemmed from this time.
Image courtesy of MICC Ltd.
The curve as we see it at present (see graph above) has turn into the usual scale for measurement of fireside test severity and has proved related for many above floor cellulosic buildings. When elements, buildings, parts or systems are examined, the furnace temperatures are managed to evolve to the curve with a set allowable variance and consideration for preliminary ambient temperatures. The standards require elements to be examined in full scale and beneath situations of assist and loading as defined so as to characterize as precisely as possible its functions in service.
This Standard Time Temperature testing protocol (see graph right) is adopted by virtually all countries around the globe for fire testing and certification of virtually all constructing structures, components, methods and elements with the fascinating exception of fireplace resistant cables (exception in USA, Canada, Australia, Germany, Belgium and New Zealand where fire resistant cable systems are required to be examined and approved to the Standard Time Temperature protocol, similar to all different building constructions, components and components).
It is essential to understand that utility standards from BS, IEC, ASNZS, DIN, UL and so forth. where fire resistive cables are specified to be used, are only ‘minimum’ requirements. We know right now that fires aren’t all the identical and research by Universities, Institutions and Authorities around the globe have identified that Underground and a few Industrial environments can exhibit very different fire profiles to these in above ground cellulosic buildings. Specifically in confined underground public areas like Road and Rail Tunnels, Underground Shopping centers, Car Parks fire temperatures can exhibit a really fast rise time and may reach temperatures properly above these in above ground buildings and in far much less time. In USA at present electrical wiring techniques are required by NFPA 502 (Road Tunnels, Bridges and different Limited Access Highways) to resist fireplace temperatures as much as 1,350 Degrees C for 60 minutes and UK British Standard BS8519:2010 clearly identifies underground public areas corresponding to automobile parks as “Areas of Special Risk” the place extra stringent test protocols for important electrical cable circuits might need to be thought of by designers.
Standard Time Temperature curves (Europe and America) plotted in opposition to common BS and IEC cable exams.
Of course all underground environments whether or not highway, rail and pedestrian tunnels, or underground public environments like purchasing precincts, automotive parks and so forth. could exhibit different hearth profiles to these in above ground buildings because In these environments the warmth generated by any fireplace can not escape as easily as it might in above floor buildings thus relying more on warmth and smoke extraction gear.
For Metros Road and Rail Tunnels, Hospitals, Health care services, Underground public environments like buying precincts, Very High Rise, Theaters, Public Halls, Government buildings, Airports etc. this is significantly necessary. Evacuation of these public environments is often slow even during emergencies, and it’s our duty to make sure everyone is given the perfect likelihood of secure egress during fire emergencies.
It is also understood today that copper Fire Resistant cables the place put in in galvanized metal conduit can fail prematurely during fire emergency due to a reaction between the copper conductors and zinc galvanizing inside the metal conduit. In 2012 United Laboratories (UL®) in America eliminated all certification for Fire Resistive cables the place installed in galvanized metal conduit for that reason:
UL® Quote: “A concern was delivered to our consideration related to the efficiency of those products within the presence of zinc. We validated this discovering. As a result of this, we modified our Guide Information to point that every one conduit and conduit fittings that are available contact with fire resistive cables ought to have an interior coating freed from zinc”.
Time temperature profile of tunnel fires using cars, HGV trailers with totally different cargo and rail carriages. Graph extract: Haukur Ingason and Anders Lonnermark of the Swedish National Testing and Research Institute who introduced the paper on the First International Symposium in Prague 2004: Safe and Reliable Tunnels.
It would seem that some Standards authorities around the world may have to evaluate the current check methodology presently adopted for fireplace resistive cable testing and perhaps align the efficiency of Life Safety and Fire Fighting wiring techniques with that of all the other fireplace resistant buildings, components and systems so that Architects, constructing designers and engineers know that after they need a fire ranking that the important wiring system will be equally rated.
For many power, management, communication and data circuits there’s one expertise out there which may meet and surpass all current fire exams and applications. เกจวัดความดันpressuregauge is a solution which is regularly utilized in demanding public buildings and has been employed reliably for over 80 years. MICC cable technology can provide a complete and full answer to all the problems associated with the fire security risks of recent flexible organic polymer cables.
The metal jacket, magnesium oxide insulation and conductors of MICC cables make positive the cable is effectively fire proof. Bare MICC cables haven’t any natural content so merely can not propagate flame or generate any smoke. The zero fuel-load of those MICC cables ensures no heat is added to the hearth and no oxygen is consumed. Being inorganic these MICC cables can not generate any halogen or toxic gasses at all including Carbon Monoxide. MICC cable designs can meet all of the present and building fireplace resistance performance standards in all international locations and are seeing a significant enhance in use globally.
Many engineers have previously thought-about MICC cable know-how to be “old school’ but with the brand new research in hearth efficiency MICC cable system are now proven to have far superior fire performances than any of the newer extra trendy flexible hearth resistant cables.
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