A confined space means a space that has all three of the following characteristics:

  • Is large enough and so configured that an employee can enter and perform assigned work; and  
  • Is not designed for continuous employee occupancy; and
  • Has limited or restricted means for entry or exit. Confined spaces typically include storage tanks, deep trenches, tank trucks, pits, ventilation and exhaust ducts, budding crawl spaces, sewers, pumping stations with wet wells, tunnels, underground utility vaults, manholes, vats, and boilers.

 

Confined Space Hazards

Some confined space openings are small in size, making passage difficult for workers, tools, and lifesaving equipment that would be necessary in the event of a rescue operation. In other cases, the size of the confined space is not a problem, but access to the opening requires the use of ladders, hoists, or other equipment. Consequently, entry and escape can be difficult.

By nature, confined spaces can be hazardous due to:

  • Space configurations such as small openings and inwardly converging walls, which can trap an entrant, restrict easy entry and exit, or impede rescue.
  • Atmospheric hazards such as gasoline tank vapors, combined with limited ventilation. Such conditions can cause asphyxiation or explosion.
  • Physical hazards, such as unstable grain contained in silos, which can engulf a worker.
  • All other serious hazards associated with general industry, such as electrical equipment, moving machinery, falling objects, and wet or slippery surfaces.

 

Types of Confined Spaces


There are two types of confined spaces. Those that require a permit for entry are classified as permit-required confined spaces (PRCS) and those that can be entered without a permit are called non-permit confined spaces (NPCS).

A permit-required confined space fits the definition of a confined space and has one or more of the following characteristics:

  • Contains or has a potential to contain a hazardous atmosphere (e.g., paint thinner).
  • Contains a material that has a potential for engulfing the entrant (e.g., liquid, soil).
  • Contains inwardly converging walls or a floor that slopes downward and tapers to a smaller cross-section where an entrant could be trapped or asphyxiated.
  • Contains any other recognized serious safety or health hazard (e.g., unsafe temperature, electrical shock, corrosive chemicals).

A non-permit confined space fits the definition of a confined space but does not contain or have the potential to contain any atmospheric hazard capable of causing death or serious physical harm.

 

Training

For affected departments, proper and thorough training shall be given to all affected personnel which includes entrants, standby persons, attendants, entry supervisors, and rescuers.  Rescue shall be held:

  • Before doing work within a confined space
  • Whenever there is change of work
  • Whenever the conditions and hazards within the space change
  • Whenever an employer has a reason to believe that an employee is not following established guidelines
  • Whenever there are new procedures or operational changes
  • Annually for rescue team members

 

Resources and References