Confined space #2: Limited space – Synthesis

How is working in dangerously limited spaces?

  • Many workers are injured and die each year while working in limited spaces. An estimated 60% of the deaths were among rescuers. A limited space can be more dangerous than regular work spaces for a variety of reasons. In order to effectively control the risks associated with working in a cons restricted space, it is necessary to carry out hazardous restricted space appraisals and implement your work zone control program. Before combining this program, be sure to review the specific regulations that apply to your workplace. All regulatory areas in Canada have restrictions on space intrusion. Regulations may vary slightly by authority. A contact list for the legal areas is available in the OSH response documents the Government Office of Canada is responsible for OH&s. Additional information is available at “OSH Answers document Confined Space – Program”.
  • If limited space is not guaranteed to be safe by giving “precaution” warnings, workers should not enter this space until safety is carried out by another means.

What is limited space?

  • In general, limited space is enclosed or partly surrounded:
    • Not primarily designed or intended for use by
    • Have a limited entrance or exit according to location, size, or vehicle
    • There may be a risk to the health and safety of anyone entering, due to one or more of the following factors:
      • By design, construction, location or atmosphere
      • By the materials or accessories in it
      • By the working activities carried out in it, or
      • By the mechanical details, or the dangers present…
  • Enclosed spaces can be under or on the ground.Enclosed spaces can be found in most workplaces. A limited space, despite its name, is not necessarily small. Examples of restricted spaces include cylinders, barrels, hoppers, utility storage, tanks, tanks, tanks, sewers, pipes, axle, truck or rail cars, aircraft wings, boilers, manholes, manholes, and containers. Ditches and trenches can also be a limited space when approaching or approaching.
Areas considered restricted spaces
Areas considered restricted spaces

What dangers in limited space?

  • All hazards found in ordinary working spaces can also be found in a limited space. However, they can be more dangerous in a limited space than in a regular space.
  • Hazards in enclosed spaces may include:
    • Poor air quality: There may be an insufficient amount of oxygen for workers to breathe. The atmosphere can contain a poison that can make workers sick or even make workers lose consciousness. Natural ventilation is often not enough to maintain good quality air for breathing.
    • Chemical exposure due to skin contact or ingestion as well as inhalation of ‘bad’ air.
    • Fire: There may be explosive/flammable air due to flammable liquids, flammable gases and dust that if burned will lead to fire or explosion.
    • Process-related hazards such as excess chemicals, supply pipeline leakage.
    • noise.
    • Safety hazards such as movement between parts of the device, structural hazards, entanglements, slips, falls.
    • Radiation.
    • Extreme temperatures cover both the atmosphere and the surface.
    • Move or pour materials in large quantities.
    • The failure of the barrier leads to overflowing water or a leakage of free-flowing liquid.
    • Uns controlled energy includes electric shocks.
    • eyesight.
    • Biological risk.
Dangers in limited space
Dangers in limited space

Why is limited space more dangerous than regular space?

  • Many factors need to be evaluated when understanding the dangers in a limited space. Errors in identifying or evaluatiing potential hazards can have more serious consequences. In some cases, conditions in a limited space are always extremely dangerous. In other cases, conditions are life-threatening under unusual circumstances. This diversity and un predictable is why dangerous assessment is extremely important and must be taken seriously once at a time.
  • There are several examples as follows:
    • The entrance/exit of closed spaces may not allow workers to exit at the right time if there is a spill or pipe breakage.
    • Difficulty when workers try to escape.
    • The rescue of the victim is more difficult. The interior structure of the limited space usually does not allow the easy movement of people or equipment in it.
    • Natural ventilation is often insufficient to maintain air with breathing quality. The structure inside the space is limited not to allow the air to move easily.
    • Working conditions can change very quickly.
    • Space outside of a limited space can affect conditions inside enclosed spaces and vice versa.
    • Working activities can produce other hazards from the beginning.

What to do when preparing to enter enclosed spaces?

  • It is important to keep in mind that each time workers plan to enter any work space, it is necessary to determine whether the working space is considered a limited space. Make sure to always follow a program that monitors and assesses the dangers of restricted spaces. See “OSH Answers document Confined Space – Program” for more information.
  • The next question to ask is – Is it absolutely necessary for work to be done in limited spaces? In many cases when there are deaths in limited, re-defined spaces, work can be done outside of limited space!
  • Before entering any restricted space, a trained and experienced person should identify and assess all existing hazards and potential risks in limited spaces. Evaluate activities inside and outside enclosed spaces.
  • Air quality check: Air in enclosed spaces must be checked from outside enclosed spaces before entering enclosed spaces. Care should be taken to ensure that the air is inspected in a limited space – between the sides and from top to bottom. A trained employee using a gas detector with a probe and a remote sampling line should conduct an air quality check. Always make sure the gas detector is properly tested and maintained. Sampling should show that:
    • Oxygen content within safe limits – not too little and not too much. Check with oxygen meter
    • No toxic atmospheres (toxic gases, flammable atmospheres). Check with multi-indicators, toxic gas detectors and flammable gas detectors
    • The ventilation device works normally.
  • The results of these hazard tests must be written on the License to enter restricted spaces along with the devices or methods used to perform the tests. Please see more at “OSH Answers document Confined Space – Program” on the issue of permits to restricted spaces.
  • Air inspections may need to be continuous depending on the nature of the potential hazards and the nature of the work. Conditions can vary while workers are in limited spaces and sometimes a dangerous atmosphere is created by working activities in limited spaces.
Handheld gas detection detectors for limited space
Handheld gas detection detectors for limited space

Refer to mangrove gas detectors used in enclosed spaces

How to control danger in limited space?

  • Traditional methods of toxic control applied in normal work zones can be effective in a limited space. These include technical control, administrative control and personal protective equipment. Technical controls are designed to eliminate hazards while administrative controls and personal protective equipment try to minimize exposure to hazards.
  • However, often because of the limited nature of the space and depending on the hazard, special precautions are required differently from those in a normal working area. The technical control commonly used in enclosed spaces is mechanical ventilation. The Entry Permit System is an example of administrative control used in restricted spaces. Personal protective equipment (protective masks, gloves, ear plugs) are often used in enclosed spaces.

How is air quality maintained?

  • Natural ventilation (natural airflow) is often unreliable and insufficient to maintain air quality. Forced ventilation (fans, fans) is often necessary to maintain air quality.
    • If there is forced ventilation, a warning system is required to immediately notify workers in case of risk or problem in the ventilation equipment.
    • Care should be taken to ensure the air supplied by the ventilation system to the restricted space is ‘clean’ throughout the space.
    • Easy movement of air in enclosed spaces should be considered because the danger of “toxic airbags” remains even with the use of mechanical ting.
    • Do not replace oxygen for clean air. Increasing the amount of oxygen will significantly increase the risk of fire and explosion.
    • The use of mechanical informed information should be noted in the entry permit
    • Ensure gas escapes from spaces that are limited to isolation from outside workers.

How to prevent fire and explosion in limited space?

  • Work using fire or in causing sources that can be called (hot work) should not be done “normally” in a limited space, unless:
    • All flammable gases, liquids and vapors are taken away before hot work begins. Mechanical ventilation is often used to:
  1. Keep the concentration of any toxic or flammable substance below 10% of the low LEL limit and
  2. Make sure that the oxygen content in enclosed spaces is not enriched. Oxygen content is less than 23% but remains at a level higher than 18%. (These numbers may vary slightly depending on local laws.)
  • Surfaces covered with flammable materials must be cleaned or shielded to avoid catching fire.
  • Do not bring fuel or fuel tanks into restricted spaces (e.g., gasoline, propane), if possible. Make sure the welding equipment is in good condition.
  • Where appropriate, use anti-spark tools, and ensure that all devices are properly locally connected.
Limited space oxygen concentration meter
Limited space oxygen concentration meter

How to control energy sources?

  • All potentially hazardous energy sources such as electricity, mechanical, hydraulic, pneumatic, chemical, or thermal must be discharged and locked before entering enclosed spaces so that the device cannot be turned on.

What are other safety precautions?

  • Many other situations or dangers may be present in a limited space. Make sure all hazards are controlled including:
    • Any free-flowing liquids or melts must be removed from enclosed spaces to avoid the risk of drowning or suffocation.
    • All pipes must be disconnected or isolated in place. Closed valves are not enough.
    • There are fences to prevent any freely melting liquids or substances from entering enclosed spaces.
    • The opening of doors to enter and exit enclosed spaces must be large enough to allow people to use protective equipment.

Refer to the additional Rescue tripod for working in enclosed spaces


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