PVC Pipe

PVC (polyvinyl chloride) is a thermoplastic material, which comprises 57% chlorine (obtained from industrial grade salt) and 43% carbon (obtained mainly from oil/gas through ethylene). This flexible material is commonly used as a replacement for copper and aluminium pipes in several areas. PVC Pipes are used for plumbing and drainage replacing metal piping. PVC is also used as the insulation on electrical cables such as teck; PVC used for this purpose needs to be plasticized. Flexible PVC coated wire and cable for electrical use has traditionally been stabilised with lead, but these are being replaced with calcium-zinc based systems. In a fire, PVC-coated wires can form hydrogen chloride fumes; the chlorine serves to scavenge free radicals and is the source of the material’s fire retardance. While hydrogen chloride fumes can also pose a health hazard, it dissolves in moisture and breaks down onto surfaces, particularly in areas where the air is cool enough to breathe and is not available for inhalation. Frequently in applications where smoke is a major hazard (notably in tunnels and communal areas), PVC-free cable insulation is preferred, such as low smoke zero halogen (LSZH) insulation. Plastic pipes exposed to fire will react differently according to the type of plastic they are made from. Some will soften and then char as the fire progresses; others will soften and melt. If not, properly fire stopped these pipes may burn out and leave a passage for fire into adjoining rooms and allow a fire to quickly spread. Fire collars and fire sleeves with intumescent materials are usually used to squeeze the pipe shut, completely sealing it before the fire can pass through. Because different types of plastic can react to fire in different ways, you must ensure the fire collar you choose is tested and approved for the type of plastic or make of pipe you are using.