Essential guidance for controlling atmospheric hazards, isolating energy, managing safe entry and preparing an effective rescue arrangement.
Independent HSE guide10 min readHigh Risk
SERNEM • Quick Technical Reference
Confined Space Entry: essential answers
These answers summarize this guide; they do not replace a work permit, legal compliance decision or site-specific risk assessment.
What does this activity involve?
Confined spaces are not designed for continuous occupancy, may have restricted entry or exit, and can contain serious atmospheric or physical hazards. Entry should take place only after hazards are evaluated, the space is isolated, acceptable atmospheric conditions are established and the permit process is completed.
What are the main hazards?
• Oxygen deficiency or oxygen enrichment
• Toxic or flammable atmosphere
• Unexpected energy or product release
• Moving mechanical equipment
See the full hazard list below.
What are the essential controls?
• Evaluate the space and determine whether it is a permit-required confined space.
• Prepare and authorize an approved confined-space entry permit before entry.
• Isolate all energy, pressure, chemical and product sources.
• Test the atmosphere before entry and throughout the work using suitable instruments.
The full control measures are listed below.
What should be checked before work?
✓ The space has been classified and hazards evaluated
✓ The entry permit is approved and available at the entry point
✓ LOTO and mechanical isolations have been verified
✓ The gas detector has been checked and readings recorded
✓ The ventilation system is operating
✓ Entrants, attendant and entry supervisor have been identified
The complete checklist appears further down this page.
Confined spaces are not designed for continuous occupancy, may have restricted entry or exit, and can contain serious atmospheric or physical hazards. Entry should take place only after hazards are evaluated, the space is isolated, acceptable atmospheric conditions are established and the permit process is completed.
Main Hazards
• Oxygen deficiency or oxygen enrichment
• Toxic or flammable atmosphere
• Unexpected energy or product release
• Moving mechanical equipment
• Engulfment, entrapment or crushing
• Restricted entry and exit
• Heat stress and inadequate ventilation
• Unprepared or delayed rescue response
Required PPE
✓Safety helmet
✓Safety footwear
✓Suitable gloves
✓Eye and face protection
✓Full-body harness where retrieval is required
✓Respiratory protection when specified by the assessment
Essential Controls
1Evaluate the space and determine whether it is a permit-required confined space.
2Prepare and authorize an approved confined-space entry permit before entry.
3Isolate all energy, pressure, chemical and product sources.
4Test the atmosphere before entry and throughout the work using suitable instruments.
5Provide continuous and adequate mechanical ventilation when required.
6Maintain a trained attendant outside the space for the duration of entry.
7Provide reliable and continuous communication with authorized entrants.
8Prepare a practical rescue plan with suitable equipment, competent personnel and response methods.
Common Mistakes
×Testing the atmosphere only before entry
×Relying only on closed valves for isolation
×Assigning unrelated duties to the attendant
×Entering without a workable rescue plan
×Using a gas detector without valid calibration or bump testing
×Failing to reassess the permit when conditions change
Pre-entry Checklist
✓The space has been classified and hazards evaluated
✓The entry permit is approved and available at the entry point
✓LOTO and mechanical isolations have been verified
✓The gas detector has been checked and readings recorded
✓The ventilation system is operating
✓Entrants, attendant and entry supervisor have been identified
✓The communication method has been tested
✓Rescue equipment and rescue personnel are ready
Rescue Readiness
A rescue plan must be workable, not merely documented. Before entry, verify the rescue method, equipment suitability, response time, communication arrangements and the availability of retrieval systems such as a tripod or winch where required. The attendant must not enter the space to attempt an unauthorized rescue.
Technical References
OSHA links lead to official US regulations. Always confirm local legal requirements, scope of applicability, and site-specific procedures. Other listed sources remain informational references until their official links are verified.