Dust, explosions

The explosive limit range for PVC dust: lower limit of 63–86 g/m3, upper limit of 500 g/m3.

The possibility of PVC resin exploding is very low. However, for any powdered material, it is necessary to avoid the formation of dust clouds and minimize ignition sources as much as possible. PVC dust poses an explosion risk, but high energy (1500–10000 J) is required to ignite particles of 20–100 μm in size; therefore, there is no significant explosion hazard associated with polyvinyl chloride. In fact, there are no reports of explosions involving polyvinyl chloride resin. The properties of PVC powder as listed in \"Polyvinyl Chloride Production and Operation\" compiled by Zheng Shizi, Yan Cainan, and others are shown in the table below: Name, Flash point, Auto-ignition point, Explosion range, Other characteristics. For PVC powder, the decomposition temperature is 130–160°C (not the auto-ignition point); the lower limit is 63–86 g/m3, and the upper limit is 500 g/m3. Once ignited, it becomes self-igniting. The flash point refers to the lowest temperature at which a mixture of a hazardous substance and air can catch fire when exposed to a flame or due to a large release of vapor – that is, combustion occurs without spreading and then immediately stops. It is an important indicator for determining the fire hazard of a compound. Autoignition point – refers to the temperature at which a hazardous material catches fire without being in contact with a source of fire (or sparks). Explosion range – refers to the range in which the gas can explode in air (or oxygen), with upper and lower limits. The hazard degree H = (upper explosion limit – lower explosion limit) / lower explosion limit. 【The higher the value of the explosion hazard degree H, the greater the risk of explosion. 】 In addition, according to the fire protection design specifications for various PVC production workshops and warehouses, areas handling acetylene, vinyl chloride, polymerization processes, stripping operations, and calcium carbide require Class A fire protection measures, while drying and packaging workshops only need Class C fire protection measures; PVC warehouses can suffice with Class D fire protection measures. PVC dust is concentrated in the drying and packaging workshops, where there are no very strict fire prevention requirements; this also indicates that the possibility of a deflagration caused by PVC dust is very low.