Working in Confined Spaces: Risks and Safety Precautions

Working in confined spaces presents serious safety risks that require strict protocols and specialized equipment to protect workers from atmospheric hazards, engulfment, and other life-threatening conditions. These environments – including tanks, manholes, sewers, and storage vessels – demand comprehensive safety measures due to their restricted access and potential for dangerous atmospheric conditions.

In this guide, we’ll explore what defines a confined space according to OSHA standards, examine the primary risks workers face, and outline essential safety precautions including monitoring equipment and entry procedures.

What Is a Confined Space According to OSHA Standards?

OSHA defines a confined space as an area with: 

• limited entry and exit points
• sufficient size for human occupation
• … but not designed for continuous use  

Common examples include storage tanks, utility vaults, pipelines, and underground chambers that workers must enter for maintenance, inspection, or repair tasks.

The distinction matters when determining if a space requires a permit. A permit required confined space contains or has the potential for hazardous atmospheres, engulfing materials, serious physical hazards, or configurations that could trap workers.

Non-permit confined spaces lack these specific hazards under normal conditions. However, conditions can change, transforming a non-permit space into one requiring full permit procedures.

What Are the Primary Atmospheric Hazards in Confined Spaces?

Atmospheric dangers represent the most significant threat to worker safety in confined spaces. Oxygen deficiency below 19.5% or enrichment above 23.5% creates immediate life-threatening conditions that can cause unconsciousness within seconds.

Toxic gases pose another critical risk. Hydrogen sulfide, carbon monoxide, and methane frequently accumulate in confined spaces, causing asphyxiation or creating explosive atmospheres. These gases often have no warning properties – hydrogen sulfide’s distinctive “rotten egg” smell disappears at dangerous concentrations, giving workers no warning. 

To put this in perspective, hydrogen sulfide at just 100 parts per million can cause immediate eye irritation, while concentrations above 500 ppm can lead to unconsciousness and death within minutes.

Engulfment hazards from liquids or free-flowing solids like grain create additional atmospheric concerns. These materials can displace oxygen or trap workers, leading to suffocation even in spaces that initially had safe atmospheric conditions.

What Confined Space Air Monitor and Safety Equipment Is Required?

Atmospheric monitoring equipment forms the foundation of confined space safety programs. Multi-gas detectors must continuously monitor oxygen levels, combustible gases, and toxic substances throughout the entry period, not just during initial testing.

Proper monitoring requires testing the atmosphere at different levels within the space. Gases have different densities – some settle at the bottom while others rise to the top. 

Ventilation equipment plays a critical role in maintaining safe atmospheric conditions. Forced-air systems help dilute contaminants and maintain adequate oxygen levels, especially in permit required confined spaces where natural ventilation is insufficient.

Personal protective equipment must match the specific hazards identified during pre-entry assessment. This includes appropriate respirators, harnesses for retrieval systems, and communication devices to maintain contact with attendants outside the space.

What Does the Confined Space Entry Procedure Involve?

The confined space entry procedure begins with a comprehensive hazard assessment to determine if the space requires a permit. This evaluation examines atmospheric conditions, physical hazards, and the potential for conditions to change during work activities.

For permit required spaces, a written permit must be completed before entry. This document identifies the entrants, attendants, entry supervisors, and specific safety measures required for the work. The permit serves as a checklist ensuring all safety precautions are in place.

Atmospheric testing must occur before entry and continue throughout the work period. Testing follows a specific sequence: oxygen content first, then combustible gases, followed by toxic substances. This order prevents potential ignition from testing equipment in oxygen-enriched or combustible atmospheres.

An attendant must remain outside the confined space throughout the entry period. This person monitors conditions, maintains communication with entrants, and initiates rescue procedures if needed. The attendant cannot enter the space or be assigned other duties that would interfere with monitoring responsibilities.

Rescue planning represents a critical, often overlooked component. Non-entry rescue methods using retrieval systems are preferred, as rescue attempts account for a significant percentage of confined space fatalities.

Conclusion

Keeping workers safe in confined spaces requires an approach combining proper hazard identification, atmospheric monitoring, and emergency preparedness. The investment in proper equipment, training, and procedures is essential when considering the severe consequences of atmospheric hazards and engulfment risks. 

Maintaining rigorous safety standards and staying current with evolving monitoring technologies is crucial for protecting workers in these environments.

Tyler O'Brien

Tyler is a results-driven marketing professional specializing in the industrial gases and equipment industry, bringing his 10 years of technical expertise and digital marketing acumen to the complex industrial gas B2B environment.