Characteristics of fire resistant wire and cable
1, the introduction
Fire retardant (Flame proof) wire and cable for the fire prevention performance is the floorboard of the wire and cable, usually divided into two categories, Flame retardant cable and fire-resistant wire and cable. Starting from the fire security and its lifesaving, more and more demand for wire and cable fire prevention performance, such as:
Flame retardant (Flame retardancy) - block and delay the spread of Flame along the wire and cable, fire not to expand.
Refractory (Fire hold) - in the case of flame can keep a certain time of running, that maintain integrity of Circuit (Circuit integrity).
Halogen halogen Free (Free) - a wire and cable materials do not contain halogen, its low corrosive products of combustion.
Low halogen (Low halogen) - a wire and cable materials can contain halogen, but the content is Low.
Low smoke, Low smoke), wire and cable produce less smoke when burning, the light transmittance is higher.
LOW toxicity, LOW toxicity), wire and cable materials produced by the burning gas LOW toxicity.
The research and development of flame-retardant and fire-resistant wire and cable in China began in 1982. After five years of time, i.e., in 1987, many cable manufacturers have been put into production and for the user. For the naming and the characteristics of the combustion model was more chaotic situation, the author puts forward to burning combustion test method for wire and cable, the classifying fire retardant wire and cable, use the first letters to Chinese pinyin as corresponding prefix of ordinary wire and cable type. Flame retardant wire and cable type of model of ZR and fire-resistant wire and cable model NH has been in use today.
As fire retardant wire and cable in the development, many new advances in the study of the original model has not apply. Combined with production manufacturers more and more, in formulating enterprise standards, about the model, to get new confusion again. Is the most outstanding performance, the combustion characteristic of wire and cable are the same, but different name and model number. The industry and user demand change this situation, hope to unified model of them. To this end, the paper put forward the fire wire and cable model establishment method, reference for compiling enterprise standards or industry standards in the future.
2, fire prevention principle of wire and cable model's establishment
(1) a model corresponds to a combustion characteristic, has the corresponding test methods and specific indicators can examination, and the first Chinese pinyin letters, simplified as much as possible.
(2) model with prefix method in ordinary wire and cable model before.
(3) the combustion characteristic of ordinary wire and cable inherent, not to other models.
(4) supplement for the development of leeway.
At present our country standard and IEC international standard is still some difference, because some of the standard, issued by IEC standards in our country, based on the principle of equivalent to adopt international standards, the difference will be eliminate in the future.
3, model and method of use
3.1 about flame retardant (ZURAN)
According to IEC 332, flame retardant with single or fascicles. More than a decade ago, China's main wire and cable for polyvinyl chloride (PVC), chloroprene rubber contain LuZhiPin, such as through a single vertical burning test is the basic requirements in the product standard, so there is no need to give model of single flame retardant. The bundle C as the basic requirement of the flame retardant wire and cable, the class B and class A as A flame retardant user must be specified requirements. Therefore, the flame retardant (ZURAN) the first letter of ZR as model is prevalent.
Now the situation is different. Polyolefin, such as polyethylene, polypropylene, ethylene propylene, natural yiding benzene is flammable material, such as when its flame retardant products can pass the single vertical burning test will be given, to phase difference with the original flammable characteristics. This model with Z. Into A bundle of burning with A flame retardant, flame retardant, flame retardant C B, flame retardant class D, therefore with ZA and ZB, ZC, lh-zd models to distinguish. Flame retardant of class D new proposals for IEC, suitable for outer diameter 12 mm and the wire and cable. The nonmetal material of the sample used to volume was only about a third of the class C is 0.5 L/m. Time to 20 min and requirement for fire burning height less than 2.5 m is the same as the class C. Because the proposal is yet to be adopted by a vote.
In addition, IEC332-3 has A regulation, namely when making class A test, if the sample get interval arrangement (there is A core of conductor is greater than 35 was occasion) in front of the standard ladder arrangement not bottom, can be arranged at the back, and expressed in AF/R. Or use wide type of ladder (0.8 m wide) all rows in front of the ladder (AF), and with double burner for the fire. But if large size in the standard cable ladder front row, with a single burner for the fire, still write for AF. To simplify the model, for this kind of situation both for ZA.
3.2 about refractory (NAIHUO)
According to the standard GB 12666.6 90, refractory divided into class A and class B two levels. The offering of class A fire temperature is 950