Confined Space Safety
This document will outline the basics of confined space safety, including the differences and requirements for non-permit and permit required spaces.
1. Confined Space Definition & Criteria
What defines a Confined Space?
A space is considered a confined space if it meets all three of the following conditions:
- Sized for Entry: It is large enough for an employee to bodily enter and perform work, AND
- Restricted Access: It has limited or restricted means of entry or exit, AND
- Not Designed for Continuous Occupancy: It is not designed for continuous employee occupancy.
Working Rule of Thumb: If you must use your hands to enter or exit, or if working in the space during normal operation poses inherent hazards to your well-being, treat it as a confined space.
Common Examples
Typical confined spaces across campus include:
- Tanks and storage vessels
- Boilers
- Manholes, utility vaults, and tunnels
- Grain storage bins and silos
2. Confined Space Classifications
Types of Confined Spaces
Non-Permit Required Confined Space
A space that meets the three basic criteria but does not contain, or have the potential to contain, an atmospheric or physical hazard capable of causing death or serious physical harm.
Examples: Fresh air ducts and drop ceiling spaces.
Permit-Required Confined Space
A space that contains or has the potential to contain one or more serious safety hazards.
- Hazardous atmosphere
- Engulfment hazard
- Entrapment hazards
- Other recognized serious safety or health hazards
Who is authorized to enter?
Authorized Personnel Only: Only employees who have completed the official Workplace Safety Confined Space Authorized Employee Training are permitted to enter designated confined spaces.
3. Hazards & Safety Controls
Hazardous Atmospheres
Oxygen Deficiency
< 19.5% O₂ — NOT SAFE
Potential causes include:
- Leaking natural gas lines
- Rusting metal
- Drying paint
- Fuel combustion
- Bacterial activity
- Welding or cutting activities
- Dilution by inert gases such as nitrogen or carbon dioxide
- Chemical oxygen consumption
Oxygen Enrichment
> 23.5% O₂ — FIRE & EXPLOSION HAZARD
This may be caused by leaking oxygen hoses, cylinders, or torches.
General Physical Hazards
- Engulfment: Entrapment by liquid or flowable solid contents such as water, oil, grain, or sand.
- Entrapment: Being trapped or asphyxiated due to inwardly converging walls or floor structures that slope downward to a narrow cross-section.
- Asphyxiation: Suffocation or loss of consciousness due to lack of oxygen or dangerous atmospheric conditions.
Required Control Measures
Prior to and during entry, the following controls must be applied:
- Air Monitoring: Test atmospheric conditions prior to entry and continuously as required.
- Ventilation: Use mechanical forced-air ventilation to maintain safe atmospheric conditions.
- Buddy System: Maintain a designated attendant outside the space at all times during entry.
- Entry Permit: Complete and post a fully authorized CS Entry Permit for all permit-required entries.
Before Entry: Confirm authorization, atmospheric testing, ventilation, communication, attendant coverage, and required permits.
4. Required Forms & Training Resources
Assessment & Permit Forms
Required Forms
Video Training Modules
Available Training Resources