Confined Space Hazards

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Confined SpaceHazards
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We Will Discuss

• Types of confined spaces
• Confined space hazards
• Physical reactions to atmospheric hazards
• Methods of eliminating or controlling hazards

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Typical Confined Spaces

• Utility Vault
• Culvert
• Trenches
• Manhole
• Pit
• Pipeline

• Pumping Station
• Septic Tank
• Silo
• Storage Tank
• Barges
• Sewer

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General Safety Hazards

• Mechanical hazards
• Communication problems
• Entry and exit
• Physical
• Thermal effects
• Noise
• Vibration

• General / physical
• Surface residues
• Structural hazards
• Fall hazards
• Engulfment hazards

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Atmospheric Hazards

• Oxygen Deficient Atmospheres
• Less than 19.5 by volume
• Oxygen Enriched Atmospheres
• Greater than 23.5 by volume
• Flammable Atmospheres
• Toxic Atmospheres

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AsphyxiationIs the Leading Causeof Death in
ConfinedSpaces.
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Oxygen Deficiency Can Be Caused by CONSUMPTION.

• Hot work
• Breathing
• Chemical reactions (ex. Oxidation of chemicals or
  metal)
• Biological action (ex. Decomposing organic matter)

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Oxygen Deficiency Can Be Caused by DISPLACEMENT.

• Argon
• Nitrogen
• Helium
• Carbon monoxide, carbon dioxide
• Cleaning agents, adhesives, or other chemicals

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Oxygen Deficient Atmospheres

• 19.5 Minimum acceptable oxygen level
• 15 - 19 Decreased ability to work strenuously,
  Impaired coordination
• 12-14 Respiration increases, Impaired judgment
• 10-12 Resp. increases, poor judgment, lips blue
• 8-10 Mental failure, fainting, unconsciousness,
  nausea and vomiting
• 6-8 8 minutes 100 fatal / 6 minutes - 50
  fatal / 4-5 minutes - possible recovery
• 4-6 Coma in 45 seconds, death

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Oxygen Enriched Atmospheres

• Oxygen level above 23.5.
• Causes flammable and combustible materials to
  burn violently when ignited.
• Hair, clothing, materials, etc.
• Oil soaked clothing and materials.
• Never use pure oxygen to ventilate.
• Never store or place compressed tanks in a
  confined space.

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Toxic Atmospheres

• Product stored in a confined space
• Gases released when cleaning.
• Materials absorbed into walls of confined space.
• Decomposition of materials in the confined space.
• Work performed in a confined space
• Welding, cutting, brazing, soldering.
• Painting, scraping, sanding, degreasing.
• Sealing, bonding, melting.
• Areas adjacent to a confined space.

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Carbon Monoxide

• Odorless, colorless chemical asphyxiant /
  flammable gas / by-product of combustion
• PPM Effect Time

35 Permissible Exposure Level 8
hours 200 Slight headache, discomfort 2-3
hours 400 Headache and nausea 1-2
hours 800 Headache, dizziness, nausea 45
min. 1,600 Headache, dizziness, nausea 20
min. 3,200 Headache and dizziness 5-10
min. 6,400 Headache and dizziness 1-2 min.
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Hydrogen Sulfide

• Very strong asphyxiant w/ rotten egg odor /
  flammable gas / by-product of the decomposition
  of organic matter / 4 times heavier than air
• PPM Effect Time

10 Permissible Exposure Level 8 hours 50 -
100 Mild Irritation - eyes, throat 1
hour 100 Desensitizes olfactory nerve 2-5
min. 250 - 350 Unconsciousness, death 4-8
hrs. 500 -600 Unconsciousness, death 30-60
min. gt1000 Unconsciousness, death minutes
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Flammable Atmospheres

• Critical Factors
• Oxygen content in the air.
• Flammable gases or vapors
• Flammable dust (visibility of 5 or less)
• Proper air/gas mixture can lead to explosion
• Typical Ignition Sources
• Sparking or electric tool.
• Welding / cutting operations.
• Smoking

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Lower Explosive Limit vs. Upper Explosive Limit
AIR
COMBUSTIBLE
TOO LEAN TO BURN
TOO RICH TO BURN
EXPLOSIVE RANGE
LEL
UEL
Gasoline
1.4 ?Flammable range? 7.6 by volume
100
0
100 LEL
0
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Causes of Fatalities in Confined Spaces

• 65 Hazardous atmospheres
• 13 Engulfment
• 7 Struck by falling objects
• 6 Heat stress / exposure
• 5 Electrocution
• 4 All others

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Common Factors in Confined Space Fatalities

• Failure to recognize a confined space
• Failure to recognize the hazards involved in
  confined space entry
• Tendency to trust physical senses
• Tendency to under-estimate the danger.
• Complacent attitude
• Attempt to save a co-worker

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Approximately 60 of All Confined Space
Fatalities Occur Among Would Be Rescuers!!
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Confined Space Fatalities Can Be Avoided Through

• Confined space safety training
• The implementation of a systematic approach to
  confined space entry

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Training and Education

• All workers who must enter confined spaces
• All attendants and rescue team members.
• Prior to initial work assignment.
• Retraining
• Job duties change.
• Change in permit-space program.
• New hazards are present.
• Job performance indicates deficiencies.

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Systematic Approach

• 1. Recognition
• 2. Testing, evaluation and monitoring
• 3. Control

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Recognition

• 1. Is this a confined space?
• 2. Is it a permit required confined space?
• 3. What are the hazards associated with this
  space?

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Testing, Evaluation and Monitoring

• Test the atmosphere before entry!
• Evaluate
• methods for isolating the space
• safe entry procedures
• special tools needed
• communication equipment needed
• Monitor the atmosphere continuously to determine
  any changes

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Testing The Atmosphere1910.146 App. A

• Evaluation testing
• Verification testing
• Test for at least the minimum response time of
  the instrument
• Order of testing
• Oxygen
• Combustibles
• Toxics
• Stratified atmospheres

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Always test the air at various levels to be sure
that the entire space is safe.
Good Air
Poor Air
Good air near the opening does NOT mean there is
good air at the bottom!
Deadly Air
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IDLH

• Immediately Dangerous to Life or Health
• All Confined Spaces should be considered IDLH
  until proven otherwise!

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Acceptable Atmospheric Conditions

• Oxygen concentration
• Flammable gas, vapor, or mist
• Toxic gas, vapor, or mist

• 19.5 to 23.5
• below 10 of the products LEL
• below the PEL of the product

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Approximately 1/3rd of All Confined Space
Fatalities Occur After the Space Has Been Tested
Safe for Entry.
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Control

• Ventilation
• Isolation
• PPE / Respirators
• Stand-by rescue
• Entry permitting