Smoke release

Standard Test Methodfor Heat and Visible Smoke Release Ratesfor Materials and Products, ASTM E906-83, American Society for Testing and Materials, Philadelphia, Pa., 1991. 

Cables are available in a variety of constmctions and materials, in order to meet the requirements of industry specifications and the physical environment. For indoor usage, such as for Local Area Networks (LAN), the codes require that the cables should pass very strict fire and smoke release specifications. In these cases, highly dame retardant and low smoke materials are used, based on halogenated polymers such as duorinated ethylene—propylene polymers (like PTFE or FEP) or poly(vinyl chloride) (PVC). Eor outdoor usage, where fire retardancy is not an issue, polyethylene can be used at a lower cost. 

Proprietary blend formulations based on polysulfone, polyethersulfone, and polyphenylsulfone are sold commercially by Amoco Corporation to meet various end use requirements. The blends based on polysulfone are sold under the MINDEL trademark. A glass fiber-reinforced blend based on PES is offered under the trade name RADEL AG-360. This offers most of the performance characteristics of 30% glass fiber-reinforced polyethersulfone but at a lower cost. Two blend product lines are offered based on PPSF. These are designated as the RADEL R-4000 and R-7000 series of products. The former is a lower cost alternative to RADEL R PPSF homopolymer offering most of the performance attributes unique to PPSF. The R-7000 series of resins have been formulated for use in aircraft interiors for civil air transport. They exhibit a very high degree of resistance to flammabihty and smoke release. 

C. W. Stewart, Sr., R. L. Dawson, and P. R. Johnson, Effect of Compounding Variables on the Rate of Heat and Smoke Release from Poly chloroprene Foam, Du Pont elastomer bulletin C-NL-550.871, 1974. 

When plastics are used, their behavior in fire must be considered. Ease of ignition, the rate of flame spread and of heat release, smoke release, toxicity of products of combustion, and other factors must be taken into account. Some plastics bum readily, others only with difficulty, and still others do not support their own combustion A plastic s behavior in fire depends upon the nature and scale of the fire as well as the surrounding conditions. Fire is a highly complex, variable phenomenon, and the behavior of plastics in a fire is equally complex and variable (Chapter 5, FIRE). 

ASTM Annual Book of Standards. Standard test method for heat and visible smoke release rates for materials and products. Test Method E 906-83. American Society for Testing and Materials Philadelphia, PA, 1985. 

Rate of heat calorimeters can be used to measure a number of the most important fire hazard parameters, including the peak rate of heat release, the total heat release, the time to ignition and smoke factor (a smoke hazard measure combining the total smoke released and the peak RHR [14, 18-20]). The smoke factor will give an... 

The 1988 Regulations should ideally be replaced by performance requirements based on composite specimens tested by hazard related tests e.g. rate of heat and smoke release when they become available. 

The OSU calorimeter [4] has long been used for simultaneously measuring heat and smoke release. It can also be used to measure release of combustion products. It is the basis of standard tests at both ASTM, the American Society for Testing and Materials (ASTM E906-1983), and FAA, the Federal Aviation Administration [6,7]. 

The Cone calorimeter yields smoke results which have been shown to correlate with those from full scale fires [10, 15-18]. The concept of a combined heat and smoke release measurement variable for small scale tests has been put into mathematical terms for the cone calorimeter smoke parameter (SmkPar) [10]. It is the product of the maximum rate of heat release and the average specific extinction area (a measure of smoke obscuration). The correlation between this smoke parameter and the smoke obscuration in full scale tests has been found to be excellent [10]. The corresponding equation is ... 

This parameter, the smoke parameter, is based on continuous mass loss measurements, since the specific extinction area is a function of the mass loss rate. A normal OSU calorimeter cannot, thus, be used to measure smoke parameter. An alternative approach is to determine similar properties, based on the same concept, but using variables which can be measured in isolation from the sample mass. The product of the specific extinction area by the mass loss rate per unit area is the rate of smoke release. A smoke factor (SmkFct) can thus be defined as the product of the total smoke released (time integral of the rate of smoke release) by the maximum rate of heat release [19], In order to test the validity of this magnitude, it is important to verify its correlation with the smoke parameter measured in the Cone calorimeter. 

Data measured, at each of three incident fluxes, include the maximum rate of heat release (Max RHR, in kw/m2), the total heat released after 15 min (THR015, in MJ/m2), the maximum rate of smoke release (Max RSR, in 1/s) and the total amount of smoke released after 15 min... 

Method of Test for Fire and Smoke Characteristics of Electrical Wire and Cables, 1990. Standard Method of Test for Heat and Visible Smoke Release Rates for Materials and Products, 1990. 

Vertical Tray Fire Propagation and Smoke Release Test for Electrical and Optical Fiber... 

Formula HCN MW 27.03 CAS [74-90-8] occurs in the root of certain plants, beet sugar residues, coke oven gas, and tobacco smoke released during combustion of wool, polyurethane foam, and nylon produced when metal cyanides react with dilute mineral acids colorless or pale liquid or a gas odor of bitter almond boils at 25.6°C solidifies at -13.4°C density of liquid 0.69 g/mL at 20°C and gas 0.95 (air = 1) at 31°C soluble in water and alcohol, very weakly acidic dangerously toxic and highly flammable (Patnaik, 1992). 

Although many people smoke because they believe cigarettes calm their nerves, smoking releases epinephrine, a hormone that actually creates psychological stress in the smoker, rather than relaxation. 

Note TTI, time to ignition PHRR, peak of heat release rate MAHRE, maximum average rate of heat emission THR, total heat release EHC, effective heat of combusion TSR, total smoke released. 

Several standard room/corner test protocols are now available and are specified in codes and regulations for qualifying interior finishes. For example, U.S. model building codes require that textile wall coverings for use in unsprinklered compartments meet specific performance requirements when tested according to NFPA 265. The principal requirement of these tests is that flash-over does not occur. The same codes also require that all other interior wall and ceiling finish materials comply with requirements based on NFPA 286, including a limit on the total smoke released. 

FIGURE 21.5 Smoke-release requirements for cables in the NEC, with corresponding hierarchy (in order of decreasing flame-spread severity). 

Other test methods can also be used to assess ignitability, together with other properties. Some important ones are the cone calorimeter (ASTM E 1354,71 Figure 21.7, which has the assessment of heat and smoke release as its primary purpose) the OSU calorimeter (ASTM E 906,38 Figure 21.8, which also... 

In the early 1980s, Vytenis Babrauskas, at the NIST (then NBS), developed a more advanced test method to measure RHR the cone calorimeter (ASTM E 1354).71164 This fire test instrument can also be used to assess other fire properties, the most important of which are the ignitability (as discussed earlier), mass loss, and smoke released. Moreover, results from this instrument correlate with those from full-scale fires.165-170 To obtain the best overall understanding of the fire performance of the materials, it is important to test the materials under a variety of conditions. Therefore, tests are often conducted at a variety of incident heat fluxes. The peak rates of heat release (and total heat released) of the same materials shown in Table 21.15 at each incident flux, are shown in Table 21.16.147... 

Despite the understanding that smoke obscuration ought to be measured in a large scale, or by a method which can predict large-scale smoke release, the most common small-scale test method for measuring smoke from burning products is the traditional smoke chamber in the vertical mode (ASTM E 662)39 (Figure 21.14). The test results are expressed in terms of a quantity called specific optical density, which is defined in the test standard. This test has now been shown to have some serious deficiencies. The most important problem is misrepresentation of the smoke... 

The cone calorimeter,71 which is a dynamic flow-through fire test, can also be used to assess smoke obscuration. The rankings tend to be quite different from those found with the static smoke chamber and are much more realistic. Several empirical parameters have been proposed to make this compensation for incomplete sample consumption, including one called the smoke factor (SmkFct), determined in small-scale RHR calorimeters.188 It combines the two aspects mentioned earlier the light obscuration (as the total smoke released) and the peak RHR. 

The majority of the materials with low flame spread (or low heat release) also exhibit low smoke release. However, it has been shown in several series of room-corner test projects (with the tested material lining either the walls or the walls and the ceiling), that -10% of the materials tested (8 out of 84) exhibited adequate heat-release (or fire growth) characteristics, but have very high smoke release (Table 21.17 and Figure 21.16).189190 These materials would cause severe obscuration problems if used in buildings. A combination of this work, and the concept that a visibility of 4 m is reasonable for people familiar with their environment,191 has led all the U.S. codes to include smoke pass/fail criteria when room-corner tests are used as alternatives to the ASTM E 84 Steiner tunnel test. 

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