Life Safety and Fire Fighting Systems – The weakest hyperlink

Unlike different cables, fire resistant cables should work even when directly exposed to the fireplace 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 electric cables as fireplace resistant they’re required to endure testing and certification. Perhaps the primary frequent fireplace exams on cables had been IEC 331: 1970 and later BS6387:1983 which adopted a gasoline ribbon burner check to produce a flame in which cables had been placed.
Since the revision of BS6387 in 1994 there have been eleven enhancements, revisions or new check requirements launched by British Standards to be used and software of Fire Resistant cables however none of these appear to address the core problem that fireside resistant cables the place tested to frequent British and IEC flame take a look at standards are not required to carry out to the same hearth performance time-temperature profiles as each other construction, system or part in a constructing. Specifically, where fire resistant buildings, systems, partitions, hearth doors, fire penetrations fireplace obstacles, flooring, partitions etc. are required to be fire rated by building rules, they’re examined to the Standard Time Temperature protocol of BS476 elements 20 to 23 (also generally recognized as ISO834-1, ASNZS1530pt4, EN1363-1 and in America and Canada ASTM E119-75).
These exams are performed in massive furnaces to copy real post flashover fire environments. Interestingly, Fire Resistant cable take a look at requirements like BS 6387CWZ, SS299, IEC 60331 BS8343-1 and 2, BS8491 only require cables to be exposed to a flame in air and to decrease last check temperatures (than required by BS476 pts 20 to 23). Given Fire Resistant cables are more likely to be uncovered in the same fire, and are needed to ensure all Life Safety and Fire Fighting systems remain operational, this truth is perhaps shocking.
Contrastingly in Germany, Belgium, Australia, New Zealand, USA and Canada Fire Resistant cable methods are required to be tested to the identical fireplace Time Temperature protocol as all other 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 developing the standard drew on the steering given from the International Fire Prevention Congress held in London in July 1903 and the measurements of furnace temperatures made in lots of hearth exams carried out in the UK, Germany and the United States. The checks were described in a sequence of “Red Books” issued by the British Fire Prevention Committee after 1903 as properly as these from the German Royal Technical Research Laboratory. The finalization of the ASTM commonplace 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 exams 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 at present and the America ASTM E119 / NFPA 251 exams doubtless stemmed from this time.
Image courtesy of MICC Ltd.
The curve as we see it today (see graph above) has become the standard scale for measurement of fire take a look at severity and has proved related for most above ground cellulosic buildings. When เกจวัดแรงดันลม10bar , constructions, parts or techniques are examined, the furnace temperatures are managed to conform to the curve with a set allowable variance and consideration for preliminary ambient temperatures. The requirements require elements to be tested in full scale and underneath conditions of support and loading as outlined in order to represent as precisely as possible its capabilities in service.
This Standard Time Temperature testing protocol (see graph right) is adopted by nearly all countries all over the world for fire testing and certification of virtually all constructing structures, elements, systems and parts with the interesting exception of fire resistant cables (exception in USA, Canada, Australia, Germany, Belgium and New Zealand where fireplace resistant cable techniques are required to be tested and accredited to the Standard Time Temperature protocol, similar to all different building constructions, parts and components).
It is necessary to grasp that software standards from BS, IEC, ASNZS, DIN, UL and so on. the place hearth resistive cables are specified for use, are solely ‘minimum’ necessities. 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 completely different hearth profiles to these in above floor cellulosic buildings. Specifically in confined underground public areas like Road and Rail Tunnels, Underground Shopping facilities, Car Parks hearth temperatures can exhibit a very fast rise time and might attain temperatures well above these in above floor buildings and in far less time. In USA today electrical wiring methods are required by NFPA 502 (Road Tunnels, Bridges and other Limited Access Highways) to resist hearth temperatures up to 1,350 Degrees C for 60 minutes and UK British Standard BS8519:2010 clearly identifies underground public areas such as automobile parks as “Areas of Special Risk” where extra stringent test protocols for essential electric cable circuits could need to be thought of by designers.
Standard Time Temperature curves (Europe and America) plotted in opposition to widespread BS and IEC cable tests.
Of course all underground environments whether or not street, rail and pedestrian tunnels, or underground public environments like purchasing precincts, automobile parks etc. might exhibit completely different fireplace profiles to these in above floor buildings as a outcome of In these environments the warmth generated by any fire can’t escape as simply as it’d in above floor buildings thus relying more on heat and smoke extraction tools.
For Metros Road and Rail Tunnels, Hospitals, Health care facilities, Underground public environments like buying precincts, Very High Rise, Theaters, Public Halls, Government buildings, Airports and so forth. this is notably necessary. Evacuation of these public environments is often slow even during emergencies, and it’s our accountability to ensure everyone is given the perfect probability of secure egress during fire emergencies.
It can also be understood today that copper Fire Resistant cables where put in in galvanized metal conduit can fail prematurely throughout fireplace emergency due to a reaction between the copper conductors and zinc galvanizing contained in the metallic conduit. In 2012 United Laboratories (UL®) in America eliminated all certification for Fire Resistive cables the place put in in galvanized metal conduit for that reason:
UL® Quote: “A concern was brought to our consideration associated to the performance of these merchandise in the presence of zinc. We validated this discovering. As a results of this, we modified our Guide Information to point that all conduit and conduit fittings that are available contact with hearth resistive cables ought to have an inside coating free of zinc”.
Time temperature profile of tunnel fires using automobiles, HGV trailers with completely different cargo and rail carriages. Graph extract: Haukur Ingason and Anders Lonnermark of the Swedish National Testing and Research Institute who offered the paper on the First International Symposium in Prague 2004: Safe and Reliable Tunnels.
It would appear that some Standards authorities around the globe could must evaluate the present take a look at methodology currently adopted for hearth resistive cable testing and maybe align the performance of Life Safety and Fire Fighting wiring techniques with that of all the other fire resistant structures, parts and methods in order that Architects, building designers and engineers know that after they need a fireplace rating that the essential wiring system might be equally rated.
For many energy, control, communication and knowledge circuits there’s one know-how available which might meet and surpass all present fireplace tests and purposes. It is an answer which is incessantly used in demanding public buildings and has been employed reliably for over eighty years. MICC cable expertise can present a total and full answer to all the problems associated with the hearth safety dangers of recent flexible organic polymer cables.
The metallic jacket, magnesium oxide insulation and conductors of MICC cables ensure the cable is effectively fire proof. Bare MICC cables haven’t any natural content so simply can not propagate flame or generate any smoke. The zero fuel-load of these MICC cables ensures no heat is added to the fire and no oxygen is consumed. Being inorganic these MICC cables can’t generate any halogen or poisonous gasses in any respect including Carbon Monoxide. MICC cable designs can meet all of the present and constructing fire resistance performance standards in all international locations and are seeing a big improve in use globally.
Many engineers have beforehand considered MICC cable expertise to be “old school’ however with the model new analysis in fire efficiency MICC cable system at the second are proven to have far superior fire performances than any of the newer more fashionable versatile fire resistant cables.
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