2　Terms

2.0.1　Petrochemical particulate solids

Petrochemical particulate polymer products or raw materials such as polyolefin，polyester，which may easily generate static electricity accumulating and cause dust combusting and blasting.

2.0.2　Volatile substances

Unpolymerized monomer component or adsorbed-and-fused gas in the process material.

2.0.3　Purging gas

The purging gas is supplied by the dedicated piping to silo to reduce combustible content in the silo to a safe level.

2.0.4　Silo

Vessel used for storing particulate polyolefins，polyesters，etc.

2.0.5　Conical surface discharge

Surface discharge occurred in silo between charged particulate solids on the surface of heap and the inner wall of silo.

2.0.6　Lightning-like discharge

The discharge occurred between charged particles floating in the air and the surrounding earthing conductor when the floating particles form charged dust clouds with considerable quantity and density.

2.0.7　Isolated electric conductor

Isolated conductor insulated from ground.

2.0.8　Combustible hybrid

Multiphase fluids consisting of combustible dust，air and one or several combustible gases or combustible vapors，also referred to as hybrid mixture.