What Is a Permit-Required Confined Space?

Limited space refers to the space that is closed or partially closed, the entrance is relatively narrow and limited, and it is not designed as a fixed work place. Poor natural ventilation can easily cause the accumulation of toxic and harmful, flammable and explosive substances or insufficient oxygen content. Limited space work refers to the work activities performed by operators entering limited space.

Confined space operation

Right!

Limited space refers to the space that is closed or partially closed, the entrance is relatively narrow and limited, and it is not designed as a fixed work place. Poor natural ventilation can easily cause the accumulation of toxic and harmful, flammable and explosive substances or insufficient oxygen content. Limited space work refers to the work activities performed by operators entering limited space.

Chinese name

Confined space operation

Explanation

Import and export are relatively narrow and limited fixed workplace

Classification

Airtight equipment, etc.

Hazard

Hydrogen sulfide, carbon monoxide, carbon dioxide

Limited space is divided into three categories:

(1) Airtight equipment: such as cabins, storage tanks, vehicle tanks, reaction towers (reactors), refrigerators, pressure vessels, pipes, flues, boilers, etc .;

(2) Limited underground space: such as underground pipes, basements, underground warehouses, underground works, culverts, tunnels, culverts, pits, waste wells, cellars, sewage ponds (wells), biogas digesters, septic tanks,

Generally, the working places with limited space often contain gases such as hydrogen sulfide, carbon monoxide, carbon dioxide, ammonia, methane (biogas), and hydrogen cyanide. Among them, asphyxiating gases mainly composed of hydrogen sulfide and carbon monoxide are particularly prominent. Common limited space operations are: cleaning slurry tanks, sedimentation tanks, brewing tanks, manure tanks, sewers, manure pits, cellars, etc .; piles, shafts, mines, etc. at construction sites; reaction towers or kettles, tankers, storage tanks, steel bottles And other containers, as well as pipes, flues, tunnels, trenches, pits, wells, culverts, cabins, underground warehouses, storage rooms, barns, etc. If working in these confined spaces, poor ventilation and high concentrations of asphyxiating gas will cause the oxygen content in the air to decrease. When the oxygen content in the air drops below 16%, people can develop hypoxic symptoms; when the oxygen content drops below 10%, consciousness disturbances of varying degrees can occur, and even death; when the oxygen content drops below 6%, sudden death can occur.

GBZ / T 205-2007 "Code for Occupational Hazard Protection in Confined Space Operations" provides that continuous mechanical ventilation and regular monitoring can ensure safe operation in confined spaces. A confined space that does not require an admission permit is called a confined space that does not require admission. Confined spaces with characteristics that may cause occupational disease hazards, including entrapment to entrants, or suffocation or loss due to their internal structure, which may cause entrants to fall, or contain other serious occupational hazard factors, are called admission confinement Space (referred to as confined space for short). ^[1]

1. Poisoning Hazard: High concentration of harmful substances is easy to accumulate in limited space. Hazardous substances may exist in a limited space or may gradually accumulate during operation.

2. Hypoxia Hazard: Low oxygen concentration in the air can cause hypoxia.

3. Explosion hazard: There are flammable and explosive substances in the air. If the concentration is too high, it will cause explosion or combustion in case of fire.

4. Other hazards: Any other environmental condition that threatens life or health. Such as fall, drowning, object strike, electric shock, etc.