Cables flammability

Aryl Phosphates. Aryl phosphates were introduced into commercial use early in the twentieth century for flammable plastics such as cellulose nitrate and later for cellulose acetate. CeUulosics are a significant area of use but are exceeded now by plastici2ed vinyls (93—95). Principal appHcations are in wire and cable insulation, coimectors, automotive interiors, vinyl moisture barriers, plastic greenhouses (Japan), furniture upholstery, conveyer belts (especially in mining), and vinyl foams. 

Protect cables from steam, water, oil leaks, corrosive or flammable atmosphere, heat sources etc. 

Calcium carbonate - emits non-flammable gases and helps to reduce the supply of oxygen lo the burning surfaces. The FRLS cables thus produced would possess the required properties... 

However, the non-armored cables must satisfy IEEE 383 or IEEE 45 flammability requirements and other requirements specified in API RP 14F. 

When flammable materials are used, drain valves should not be located above hot pipework or equipment. A fire on an ethylene plant started when a mixture of water and naphtha was drained through a )4-in. drain valve onto pipework at 315°C. It took a long time to replace damaged control and electric cables [21J. 

Examples A, closed cell thermal insulation with high fire retardency and low smoke generation (52,54) B, pigmented APN coatings in aluminum substrates with low flammability, low flame spread, and low smoke (55) C, APN insulation and cable jacketing (56) D, open cell APN comfort cushioning (57). (Photograph courtesy of the Firestone Tire... 

This material finds use as a sealing material in automotive applications and marine motor lead wire insulation. It has also been used as the base polymer for low flammability, halogen free, cable jacketing compounds. 

Hitachi Cable Ltd. (35) has claimed that dehydrogenation catalysts, exemplified by chromium oxide—zinc oxide, iron oxide, zinc oxide, and aluminum oxide—manganese oxide inhibit drip and reduce flammability of a polyolefin mainly flame retarded with ATH or magnesium hydroxide. Proprietary grades of ATH and Mg(OH)2 are on the market which contain small amounts of other metal oxides to increase char, possibly by this mechanism. 

Primary cable trays inside of process areas, process structures, or unit battery limits should be reviewed to determine if their routing or location presents a potential fire exposure. Potential external fire exposures to cable trays are typically at those locations where flammable or combustible liquids or gases are handled, such as ... 

Wall penetrations for cables and conduits should be sealed with an approved fire retardant sealant. If conduit is used that subsequently passes through flammable areas, appropriate conduit seals must be used at the MCC terminus. 

The polyetherimide—polysiloxane multiblock copolymers are relatively hard (about 70 on the Shore D scale). Their main application is flame-resistant wire and cable covering (24), where they combine very low flammability with a low level of toxic products in the smoke. This unusual and vital combination of properties justifies their relatively high price, about 37/kg, at a specific gravity of about 1.2. 

Because of their flexibility, low flammability, and resistance to oil, fuel, and chemicals, FTPEs find use in electrical and wire and cable industries as wire coating and as sheathing and coating of cables.74-75... 

Laboratory Flammability Tests for Wire and Cable Materials.794... 

LABORATORY FLAMMABILITY TESTS FOR WIRE AND CABLE MATERIALS... 

Cone calorimetry according to the ASTM E1354138 or ISO 5660139 standards are commonly used in the laboratory to screen flammability of materials by measuring heat release characteristics of the compound.116140 This device is similar to FPA but does not have the versatility of FPA. The cone calorimeter can determine the ignitability, heat release rates, effective heat of combustion, visible smoke, and C02 and CO development of cable materials. This test has been used extensively for wire and cable material evaluation. The microscale combustion calorimeter (MCC), also known as pyrolysis combustion flow calorimeter (PCFC), was recently introduced to the industry for screening heat release characteristics of FR materials.141142 This device only requires milligram quantities of test specimen to measure the heat release capacity (maximum heat release potential). Cone calorimetry and MCC have been used in product development for flammability screening of wire and cable compounds.118... 

FIGURE 26.5 Relationships between LOI and HRC for pure polymers and FR compounds. (From Lin, T.S. et al., Correlations between microscale combustion calorimetry and conventional flammability tests for flame retardant wire and cable compounds, in Proceedings of 56th International Wire and Cable Symposium, 2007, pp. 176-185.) The LOI-HRC relationship for pure polymers is obtained from the literature. (From Lyon, R.E. and Janssens, M.L., Polymer flammability, Final Report DOT/FAA/AR-05/14 May, 2005.)... 

As one can see from the above discussion, establishing correlation between bench-scale flammability and cable flame tests is a difficult task because of complicated chemical and physical processes involved in the burning and combustion of polymer materials and cables. Much research is still needed to understand fundamental processes governing the flaming combustion of wire and cable compounds in actual cable designs and cable bundles in a given environment. 

Nakagawa, Y. and Komai, T., Current Japanese standards for flammability tests on electric cables, Fire Mater., 1993, 17(6), 265-270. 

Nakagawa, Y., A comparative study of bench-scale flammability properties of electric cables with different covering materials, J. Fire Sci., 1998, 16, 179-205. 

PVC-U formulations have low flammability due to the chlorine content. The addition of plasticiser in PVC-P formulations necessitates the use of flame retardant and smoke suppressant additives. These additives are known as functional fillers and a correct balance is necessary to achieve all the end-use specification requirements. They are predominately used in cable, conveyer belting and roofing membrane formulations to give resistance to fire initiation and propagation. It is also important to reduce dripping in a fire situation and that as little smoke as possible is generated. Antimony trioxide has been used extensively, usually in combination with phosphate ester plasticisers, giving excellent fire performance and mechanical properties. 

Ethylene copolymers were compared with liquid plasticisers for use as additives to improve the flexibility of poly(vinyl chloride) (PVC) for electrical cable insulation applications. The PVCs were assessed by determining smoke generation, flammability, tensile properties and the low temperature brittle point. The ethylene copolymers gave similar peak heat release rates, but the peak smoke and the total smoke generation were lower. They also gave similar or increased strength, similar elongation and flexural modulus, and lower brittle point temperatures. 4 refs. 

Oparex 15 calcined calcium sulphate (Yesos Ibericos) was evaluated as a filler in plasticised PVC cable insulation compounds in comparison with two grades of calcium carbonate. Improvements were observed in tensile, electrical and low temperature properties, flammability and heat ageing characteristics and chemical resistance for calcium sulphate filled compounds, while no significant differences in water absorption and hydrolysis were noted. Studies of rheological properties showed improved processability in mixing and extrusion trials. URALITA... 

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