Definition: Closed or partially closed, relatively isolated from the outside, only with narrow entrances and exits, operators cannot work inside for a long time, poor ventilation easily to cause toxic, harmful, flammable, explosive material accumulation or insufficient oxygen space. Difficult to rescue and easy to extend in case of accident.
Possible hazards of limited Spaces
Death by asphyxia:
Hypoxia is the leading killer of confined space. Common reasons for hypoxia in confined space are:
Metal rust consumes oxygen;
Combustion consumes oxygen;
Oxygen is replaced by other gases;
Oxygen is consumed by microorganisms;
Toxic and harmful gas poisoning, combustible gas fire:
Toxic gas (mainly CO, H2S, etc.) sources: substances used or produced in the space + external pollution sources
Sources of harmful gases (N2, CO2, O2, etc.) : excessive content leads to hypoxia, and oxygen toxicity may occur if oxygen concentration is over 40%
Sources of combustible gases and vapors: decomposition, replacement, residue (evaporation of residual components, products of chemical processes, desorption of building materials), work products
Limited space workplace:
Industrial furnace (blast furnace, converter, hot air furnace, boiler, heating furnace), tower, ball tank, gas tank, tank car, hopper (trough), pipes, flue, etc.