According to the incomplete statistics of the fire department, about 85% of the deaths in the fire were caused by the poisonous gas that was killed in the fire, the suffocation of the diffused smoke, or the inability to escape due to the invisible path. In buildings, cables are the most numerous and widely distributed cables. Flame retardancy has always been an essential element of cables.
When we use data cables, we often see the CM, CMR, CMX, etc. printed on the surface of the cable jacket. These words represent the flammability rating of the cable and undergo a series of rigorous flame-retarding tests by the UL lab. Only after passing the test can the corresponding flame retardant rating and UL number be printed on the surface of the cable jacket.
Boost level - CMP level:
This is the most demanding cable in the UL fire protection standard. The applicable safety standard is UL910. Need to pass UL air combustion test/Stone sodium duct experiment. It is perfectly flame-retardant and emits very low smoke and toxins. According to the definition of UL, a bundle of CMP cables must extinguish itself within less than 5 meters of the combustion diffusion under forced fan-intensive combustion conditions. The CMP cable uses Teflo-based chemicals to prevent the combustion from spreading and to minimize the emission of smoke and toxins. This adds a lot of cost. The CMP grade cable is used in a building where cables are laid in the ventilation return duct. In the event of a fire, the building will not be full of smoke or harmful toxins emitted by the cables.
Trunk Level - CMR Level:
This is a commercial grade cable in the UL standard. The applicable safety standard is UL1666. Need to pass UL upright burning test. The trunk level cable does not have a smoke concentration specification and is generally used for vertical and horizontal floor wiring. It has perfect flame retardant capabilities, but it does not test emitted smoke and toxins. CMR cables use halide-based chemicals such as chlorine to prevent the combustion from spreading. By definition, a bundle of CMR cables must self-extinguish within less than 5 meters of the combustion spread under forced fan combustion conditions. CMR cable jackets are generally made of a type of PVC that emits chlorine gas in the combustion chamber. Chlorine depletes the oxygen in the air and extinguishes the flame.
Commercial grade -CM grade:
This is a commercial grade cable in the UL standard. The applicable safety standard is UL1581. Need to pass UL vertical burning test. Commercial grade cables do not have smoke concentration specifications and are generally applied only to horizontal cabling on the same floor. They should not be used for vertical cabling on floors.
General-level CMG:
This is a general-purpose cable in the UL standard. The applicable safety standard is UL1581. Need to pass UL vertical burning test. General-purpose cables also do not have smoke concentration specifications. They are generally applied only to horizontal cables on the same floor and should not be used for vertical wiring on floors.
Both general-purpose (CMG) and commercial-grade (CM) are common in the horizontal alignment of buildings, and they are usually divided into smaller bundles than CMR-class cables. The CM/CMG grade cable uses a halide-based chemistry for timelines. By definition, in a small bundle of cables, the CM/CMG cable must self-extinguish within less than 5 meters of the combustion spread. The flame did not use a fan to force combustion. CM/CMG grade cable jackets are usually made of some type of PVC and emit chlorine in the combustion chamber.
Home level - CMX level:
This is a home-grade cable in the UL standard. The applicable safety standards are UL1581 and VW-1. Need to pass the vertical burning test. This grade also has no smoke or toxicity specifications and is used only in home or small office systems where a single cable is laid. This type of cable should not be laid in bundles and must be sleeved. Smoke density, halogen content, and toxicity rating. This type of cable is limited to other small applications where there is a very small number of residential or telecommunication cables in use. These applications typically use only one cable. CMX grade tools cannot be used for bundled cable applications.
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