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A fire-resistance rating typically means the duration for which a passive fire protection system can withstand a standard fire resistance test. This can be quantified simply as a measure of time, or it may entail other criteria, involving evidence of functionality or fitness for purpose.
The following depict the most commonly used international time/temperature curves:
There are many international variations for nearly countless types of products and systems, some with multiple test requirements.
Canada's Institute for Research in Construction (a part of the National Research Council and publisher of Canada's model building code – NBC) requires a special test regime for firestops for plastic pipe penetrants. Fire endurance tests for this application must be run under 50Pa positive furnace pressure in order to adequately simulate the effect of potential temperature differences between indoor and outdoor temperatures in Canada's winters. Special hoods are applied here to provide suction on the top side of a test assembly in order to reach the 50Pa pressure differential. Afterwards, a 30PSI hose-stream test may be applied.
Outdoor spray fireproofing methods that must be qualified to the hydrocarbon curve may be required to pass a host of environmental tests before any burn takes place, to minimize the likelihood of ordinary operational environments rendering a vital system component useless before it ever encounters a fire.
If critical environmental conditions are not satisfied, an assembly may not be eligible for a fire-resistance rating.
The following classifications may be attained when testing in accordance with UL 72. [2]
This rating is the requirement in data safes and vault structures for protecting digital information on magnetic media or hard drives. Temperatures inside the protected chamber must be held below 125 °F (52 °C) for the time period specified, such as Class 125-2 Hour, with temperatures up to 2,000 °F (1,090 °C) outside the vault. The temperature reading is taken on the inside surfaces of the protective structure. Maintaining the temperature below 125 °F is critical because data is lost above that temperature threshold, even if the media or hard drives appear to be intact.
This is the rating required to protect microfilm, microfiche, and other film-based information storage media. Above 150 °F (65.5 °C) film is distorted by the heat and information is lost. A Class 150-2 Hour vault must keep the temperature below 150 °F. for at least two hours, with temperatures up to 2,000 °F. (1,093.3 °C) outside the vault.
This rating is the requirement for protecting paper documents. Above 350 °F (176.7 °C) paper is distorted by the heat and information is lost. A Class 350-4 Hour vault must keep the temperature below 350 °F. for at least four hours, with temperatures up to 2,000 °F. (1,093.3 °C) outside the vault.
Typically, most countries use the building elements curve for residential and commercial spaces, which is nearly identical in most countries as that is what results by burning wood. The building elements curve is characterized jointly by, including, but not limited to, DIN4102, BS476, ASTM E119, ULC-S101, etc. For industrial facilities in the hydrocarbon and petrochemical industries, a hydrocarbon curve (such as UL 1709) is used, reflecting a more rapid temperature rise. The only commonly used exposure beyond this, apart from the more recent tunnel curves shown above, would be the jet fire exposure standards such as ISO 22899, which are used where equipment may be subject to the extreme heat and momentum effects of jet fire exposure.
During a fire in a tunnel, as well as in the petrochemical industry, temperatures exceed those of ordinary building (cellulosic) fires. This is because the fuel for the fire is hydrocarbons, which burn hotter (compare hydrocarbon curve above to ASTM E119 curve), faster and typically run out of fuel faster as well, compared against timber. The added complication with tunnels is that heat cannot escape as well as it can in open area. Instead, the fire is confined to a narrow tube, where pressure and heat build up and spread rapidly, with little room for escape and little chance of compartmentalization.
Construction of a test sample consists of a mockup of a section of concrete floor, with typical mechanical and electrical utility components (pipes and cables) penetrating the floor assembly. A firestop mortar is applied around the penetrations.
The completed test sample is inserted into a furnace such that one side is exposed to a fire. The test is terminated when the fire stops successfully meet the test criteria in minimizing the amount of heat and smoke allowed to pass through the assembly, when the fire penetrates the fire stops. This determines the fire stop F-Rating. The length of time required for a penetrant or sample on average to exceed a specified average heat rise above ambient at any single location determines the duration for the FT Rating (Fire and Temperature). If a hose-stream test is passed afterwards, the rating can then be expressed as an FTH Rating (Fire, Temperature and Hose-stream). The lowest of the three determines the overall rating.
A firewall is a fire-resistant barrier used to prevent the spread of fire. Firewalls are built between or through buildings, structures, or electrical substation transformers, or within an aircraft or vehicle.
A hydraulic fluid or hydraulic liquid is the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water. Examples of equipment that might use hydraulic fluids are excavators and backhoes, hydraulic brakes, power steering systems, automatic transmissions, garbage trucks, aircraft flight control systems, lifts, and industrial machinery.
A safe is a secure lockable enclosure used for securing valuable objects against theft or fire. A safe is usually a hollow cuboid or cylinder, with one face being removable or hinged to form a door. The body and door may be cast from metal or formed out of plastic through blow molding. Bank teller safes typically are secured to the counter, have a slit opening for dropping valuables into the safe without opening it, and a time-delay combination lock to foil thieves. One significant distinction between types of safes is whether the safe is secured to a wall or structure or if it can be moved around.
A heating element is a device used for conversion of electric energy into heat, consisting of a heating resistor and accessories. Heat is generated by the passage of electric current through a resistor through a process known as Joule Heating. Heating elements are used in household appliances, industrial equipment, and scientific instruments enabling them to perform tasks such as cooking, warming, or maintaining specific temperatures higher than the ambient.
A fire door is a door with a fire-resistance rating used as part of a passive fire protection system to reduce the spread of fire and smoke between separate compartments of a structure and to enable safe egress from a building or structure or ship. In North American building codes, it, along with fire dampers, is often referred to as a closure, which can be derated compared against the fire separation that contains it, provided that this barrier is not a firewall or an occupancy separation. In Europe national standards for fire doors have been harmonised with the introduction of the new standard EN 16034, which refers to fire doors as fire-resisting door sets. Starting September 2016, a common CE marking procedure was available abolishing trade barriers within the European Union for these types of products. In the UK, it is Part B of the Building Regulations that sets out the minimum requirements for the fire protection that must be implemented in all dwellings this includes the use of fire doors. All fire doors must be installed with the appropriate fire resistant fittings, such as the frame and door hardware, for it to fully comply with any fire regulations.
An electrical enclosure is a cabinet for electrical or electronic equipment to mount switches, knobs and displays and to prevent electrical shock to equipment users and protect the contents from the environment. The enclosure is the only part of the equipment which is seen by users. It may be designed not only for its utilitarian requirements, but also to be pleasing to the eye. Regulations may dictate the features and performance of enclosures for electrical equipment in hazardous areas, such as petrochemical plants or coal mines. Electronic packaging may place many demands on an enclosure for heat dissipation, radio frequency interference and electrostatic discharge protection, as well as functional, esthetic and commercial constraints.
Fireproofing is rendering something resistant to fire, or incombustible; or material for use in making anything fire-proof. It is a passive fire protection measure. "Fireproof" or "fireproofing" can be used as a noun, verb or adjective; it may be hyphenated ("fire-proof").
An intumescent is a substance that swells as a result of heat exposure, leading to an increase in volume and decrease in density. Intumescence refers to the process of swelling. Intumescent materials are typically used in passive fire protection and require listing, approval, and compliance in their installed configurations in order to comply with the national building codes and laws.
Fire protection is the study and practice of mitigating the unwanted effects of potentially destructive fires. It involves the study of the behaviour, compartmentalisation, suppression and investigation of fire and its related emergencies, as well as the research and development, production, testing and application of mitigating systems. In structures, be they land-based, offshore or even ships, the owners and operators are responsible to maintain their facilities in accordance with a design-basis that is rooted in laws, including the local building code and fire code, which are enforced by the authority having jurisdiction.
A firestop or fire-stopping is a form of passive fire protection that is used to seal around openings and between joints in a fire-resistance-rated wall or floor assembly. Firestops are designed to maintain the fire-resistance rating of a wall or floor assembly intended to impede the spread of fire and smoke.
Passive fire protection (PFP) is components or systems of a building or structure that slows or impedes the spread of the effects of fire or smoke without system activation, and usually without movement. Examples of passive systems include floor-ceilings and roofs, fire doors, windows, and wall assemblies, fire-resistant coatings, and other fire and smoke control assemblies. Passive fire protection systems can include active components such as fire dampers.
Within the context of building construction and building codes, occupancy is the use of a building for the shelter or support of persons, animals or property. A closely related meaning is the number of units in such a building that are rented, leased, or otherwise in use. Lack of occupancy, in this sense, is known as vacancy.
Circuit integrity is how little can a fire affect an electrical circuit's operation. It is a form of fire-resistance rating. Circuit integrity is achieved via passive fire protection means, which are subject to listing and approval use and compliance. Alternatively, cable construction and materials can achieve fire-resistance ratings on their own such as mineral-insulated copper-clad cable, or MI cable.
A fire test is a means of determining whether fire protection products meet minimum performance criteria as set out in a building code or other applicable legislation. Successful tests in laboratories holding national accreditation for testing and certification result in the issuance of a certification listing.
A combustible material is a material that can burn in air under certain conditions. A material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable material catches fire immediately on exposure to flame.
A grease duct is a duct that vents grease-laden flammable vapors from commercial cooking equipment such as stoves, deep fryers, and woks to the outside of a building or mobile food preparation trailer. Grease ducts are part of the building's passive fire protection system. The cleaning schedule is typically dictated by fire code or related safety regulations.
A building joint is a junction where building elements meet without applying a static load from one element to another. When one or more of these vertical or horizontal elements that meet are required by the local building code to have a fire-resistance rating, the resulting opening that makes up the joint must be firestopped in order to restore the required compartmentalisation.
A penetration, in firestopping, is an opening, such as one created by the use of a cast-in-place sleeve, in a wall or floor assembly required to have a fire-resistance rating, for the purpose of accommodating the passage of a mechanical, electrical, or structural penetrant.
ioSafe is a manufacturer of disaster protected hard drives and network attached storage (NAS) appliances. The company was founded in 2004 and is based in Roseville, California. ioSafe's storage systems are optimized for heat from fire and complete submersion in fresh or saltwater with the ability to recover data located on the disk drive inside.
Fire dampers are passive fire protection products used in heating, ventilation, and air conditioning (HVAC) ducts to prevent and isolate the spread of fire inside the ductwork through fire-resistance rated walls and floors. Fire/smoke dampers are similar to fire dampers in fire resistance rating, and also prevent the spread of smoke inside the ducts. When a rise in temperature occurs, the fire damper closes, usually activated by a thermal element which melts at temperatures higher than ambient but low enough to indicate the presence of a fire, allowing springs to close the damper blades. Fire dampers can also close following receipt of an electrical signal from a fire alarm system utilising detectors remote from the damper, indicating the sensing of heat or smoke in the building occupied spaces or in the HVAC duct system.
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