Gas Detection for Confined Space Entry

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Gas Detection for Confined Space Entry
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Introduction

• Gas detection with a properly calibrated
  instrument is the only sure way of knowing if
  dangerous gases are present
• Air is a mixture of gases any deviation from the
  normal poses a serious threat in the working
  environment
• Gas detection minimizes the chances of serious
  injury or death in the workplace

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We will Discuss

• Hazardous Atmospheres
• Confined Spaces
• Atmospheric Testing
• Combustible Atmospheres
• Oxygen-hazards
• Toxic Gases- hazards
• Industries for each

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JARGON

• LEL Lower Explosive Limit - LEL
• PPM Parts Per Million - toxic gas measurement
  
• PEL Permissible Exposure Limit -
  8
  hr/day - 40 hrs/wk - (OSHA)
• TWA Time Weighted Average - 8hr/day- (ACGIH)
• STEL Short Term Exposure Limit -
• 15 mins/4x shift - (w/ 1 hr break - ACGIH)
• IDLH Immediately Dangerous to Life and Health
  30 mins - (NIOSH)

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Agencies

• OSHA - Occupational Safety and Health
  Administration
• Department of Labor
• define - occupational safety and health laws
• authority - issue citations and levi fines
• MSHA - Mine Safety and Health Administration
• Department of Labor
• define - occupational / health laws - mining
• authority - issue citations and levi fines
• approval authority - underground equipment and
  respirators

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Agencies

• NIOSH - National Institute for Occupational
  Safety Health
• Department of Health and Human Services
• research and education agency - OSHA
• approval authority - respiratory protection
• NIST - National Institute of Standards and
  Technologies
• Independent Organization
• calculate / set standards - measurement
• provide tracibility Draeger Calibration Gases

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Agencies

• ACGIH - American Conference of Governmental
  Industrial Hygienists
• Independent Non-Profit Organization
• set guidelines - industrial hygiene
• HIOSH- Hawaii

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Intrinsic Approval Agencies

• MSHA Mine Safety and Health Administration
• UL Underwriters Laboratory
• FM Factory Mutual

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Hazardous Atmospheres
def atmosphere that may expose employees to the
risk of death, incapacitation, impairment of self
rescue, injury, or acute illness

• Confined Spaces, and open locations can both
  contain Hazardous Atmospheres
• Examples of these hazards are Combustibles, Toxic
  Gases and atmospheres enriched with or deficient
  in oxygen

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CONFINED SPACES
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Confined Spaces
an area that is large enough and so configured
that an employee can bodily enter and perform
work and has limited or restricted means for
entry or exit and is not designed for continuous
employee occupancy

• Hazards
• Atmospheric
• O2 deficiency
• O2 enrichment
• combustibles
• toxics
• Physical engulfment

• Fatality Factors
• failure to recognize hazards
• incorrect emergency response
• Prevention
• detection
• monitoring

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Confined Space Examples

• Storage Tanks
• Sewers
• Boilers
• Manholes
• Ship Voids
• Tunnels

• Pipelines
• Trenches
• Pits
• Silos
• Vats
• Wells

United States - any pit or trench gt4 ft. Can
be classified as a Permit Required Confined Space
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Permit Required Confined Spaces
def a confined space that has one or more of
the following characteristics

• Contains or has the potential to contain a
  hazardous atmosphere
• Contains a material that has the potential for
  engulfing an entrant
• Has an internal configuration such that an
  entrant could be trapped or asphyxiated
• Contains any other recognized serious safety or
  health hazard

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Confined Space Entry

• In the US Alone Between 1997 2001
• I Confined Space Death Occurred every Four Days.

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Confined Space Entry
Deaths by Atmospheric Hazard Types 2005
139 Incidents reported all Involving Deaths, No
Detection or ventilation was used 24 of spaces
were Toxic before entry
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Confined Spaces
Deaths by specific personnel 2005
139 Incidents Reported 139 Deaths 33
Supervisors 60 Rescuers
Tanks, vats/pits, digesters, and sewer manholes
are the most frequently encountered confined
spaces
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ATMOSPHERIC TESTING
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Atmospheric Testing
ref CFR 1910.146 (C) subsection (C) before an
employee enters the space, the internal
atmosphere shall be tested for the following
conditions in the order given

• Oxygen 19.5vol
• Combustible Gases 10 LEL / CH4
• Toxic Gases depends on gas type

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Atmospheric Testing

• Sample When / Where?
• prior to entry
• top, middle bottom
• continuously during entry
• prior to re-entry
• Sample Why?
• stratification / weights

TOP
MIDDLE
BOTTOM
ref CFR 1910.146 (c) subsection (D) there
may be no hazardous atmosphere within the space
whenever any employee is inside the space
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Atmospheric Testing

• METHANE (lighter than air)

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Atmospheric Testing

• METHANE (lighter than air)
• CARBON MONOXIDE (A Bit lighter than air)

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Atmospheric Testing

• METHANE (lighter than air)
• CARBON MONOXIDE (A Bit lighter than Air)
• HYDROGEN SULFIDE (heavier than air)

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COMBUSTIBLE ATMOSPHERES
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Fire Triangle
Portable instruments
detect the combustible gas (fuel)
fuel
air
source of ignition
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Common Combustibles

• Combustible 100 LEL
• Methane (natural gas) 5.0 vol
• Propane 2.1 vol
• Pentane (gasoline) 1.4 vol
• Butane 1.9 vol
• Hexane 1.2 vol
• Methanol 6.0 vol
• Hydrogen 4.0 vol

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Example of Combustion

• 100 LEL UEL
• 0 5.0 15
  100 Vol

(Natural Gas) Methane (CH4)
Too Lean to Burn
Explosive Mixture
Too Rich to Burn
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Example of Combustion

• LEL UEL
• 0 1.4 7.8
  100 Vol

(Gasoline) PENTANE (C5H12)
Too Lean to Burn
Too Rich to Burn
Explosive Mixture
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OXYGEN
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Oxygen Deficiency

• Risk of asphyxiation
• Caused by
• Consumption
• people
• oxidation
• Displacement
• combustion
• decomposition
• Inertion

19.5
Oxygen
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Oxygen Enrichment

• Serious fire hazard
• Materials burn much more rapidly
• Caused by
• leaking valves
• leaking cylinders

Oxygen
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Effects of Oxygen

• 23.5 Maximum safe level (OSHA)
• 23.0 Oxygen enriched - fire hazard
• 21.0 Oxygen content in Air (20.954)
• 19.5 Minimum safe level (OSHA, NIOSH)
• 17.0 Impairment of judgement begins
• 16.0 First signs of Anoxia
• 16-12 Breathing and pulse rate increase,
  coordination is impaired

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Effects of Oxygen

• 14-10 Fatigue, disturbed respiration
• 10-6 Nausea and vomiting, inability to move
  freely and loss of consciousness
• lt6 Convulsive movements and gasping respiration
  occurs respiration stops/minutes later heart
  action ceases
• 3-5 Life expectancy 3 - 5 minutes

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TOXIC GASES
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Toxic Gases

• Toxic gases are compounds of elements that pose a
  threat to human life - react in the body in a
  poisonous fashion
• Toxic gases can enter the body through various
  ways, they can be ingested, injected, or absorbed
  through the skin
• Toxic gases are often colorless and odorless
  making them a serious threat in the working
  environment
• The two most common are CO H2S

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Toxic Gases

• Chronically Toxic
• prolonged exposure
• effect on hemoglobin
• flu-like symptoms (headache, dizziness,)
• medical effect may not be felt for many years
• Carbon Monoxide (CO) most common

• Acutely Toxic
• inhibit cell respiration
• effect on enzymes
• shut down lungs and other organs
• can cause death
• Hydrogen Sulfide (H2S) most common

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Carbon Monoxide Data

• CO Colorless, Ordorless, byproduct of incomplete
  combustion
• Hazard Flammable, LEL 12.5
• Health Very Toxic (can be absorbed 200-300 time
  faster than oxygen by the hemoglobin)
• ExposuresPEL/TWA25ppm C
  200ppm IDLH 1200ppm
• Industries Steel mills, garages,
  general industries

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Effects of CO

• 25ppm Permissible exposure limit, 8 hr
• 400ppm Frontal headache in 2-3 hrs
• 1600ppm Headache and nausea 20 mins Collapse
  and death in 1-2 hrs
• 6400ppm Headache, dizziness in 1-2 mins,
  unconsciousness and death in 10-15 mins

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Hydrogen Sulfide Data

• H2S Colorless, Rotten egg smell
• Hazard Flammable, LEL 4.0
• Health Extremely Toxic, appears naturally from
  decomposition, reacts with the enzymes in the
  blood - inhibits cell respiration
• Exposure PEL/TWA 10ppm
  STEL 15ppm IDLH 100ppm
• Industries Oil and Gas, pulp and
  paper, waste water treatment

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Effects of H2S

• .13ppm - Minimal perceptible odor
• 10ppm - Beginning of eye irritation,
  permissible exposure limit
• 100ppm - Coughing, eye irritation, loss
  of sense of smell after 2-5
  minutes
• 500ppm - Loss of consciousness and
  possible death 30 mins - 1 hr

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Chlorine Gas Data

• CL2 Greenish-yellow gas with a pungent odor
• Hazard Will not explode, will react
  explosively to ammonia, turpentine fuel oil
• Health Extremely toxic
• Exposures PEL/TWA 0.5ppm
  STEL 1ppm IDLH 10ppm
• Industries Municipal pools, pulp and paper,
  water treatment plants, Hazmat

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Effects of CL2

• .5ppm - Permissible exposure Level
• 3ppm - Irritation of the mucus membranes,
  eyes and respiratory track
• 15ppm - Causes immediate irritation of the
  throat
• 30ppm - Maximum exposure for a 30
  minute period

BLEACH
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Nitrogen Dioxide Data

• NO2 yellowish-brown gas with a
  pungent, acrid odor
• Hazard will not explode
• Health Extremely toxic
• Exposures PEL/TWA 1ppm STEL 5ppm
  IDLH 20pppm
• Industries Mining and all machinery using
  diesel engines, chemical plants

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Effects of NO2

• 1ppm - Permissible exposure limit (PEL)
• 20ppm - Irritation of eyes, nose and throat
• 50ppm Chest Pain, Pulmonary Edema

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Sulfur Dioxide Data

• SO2 Colorless gas, irritating pungent odor
• Hazards will not explode, can combine with
  water to form sulfuric acid (H2SO4) - ACID
  RAIN
• Health extremely toxic
• Exposures PEL/TWA 2ppm STEL 5ppm
  IDLH 100ppm
• Industries Pulp and paper, coal fired
  power plants, fossil fuels

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Effects of SO2

• .3-1ppm - Initially detected by taste
• 2ppm - Permissible exposure limit
• 20ppm - Irritation of nose, throat and eyes
• 100ppm - Choking, Bronchial Restriction

Sulfuric Acid (H2SO4) SO2 H2O
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Ammonia Data

• NH3 colorless gas with a suffocating odor
• Hazards Difficult to burn, LEL 15
• Health extremely toxic
• Exposures PEL/TWA 25ppm STEL
  35ppm IDLH
  300ppm
• Industries Fertilizer plants,
  poultry farms, Refrigeration
  industries

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Effects of NH3

• 0-25ppm - Minor irritation of the eyes and
  respiratory tract
• 25ppm - Permissible Exposure Limit
• 50-100ppm - Swelling of the eyelids,
  conjunctivitis, vomiting, irritation of
  the throat
• 100-500ppm - Very dangerous concentrations, death
  from prolonged exposure

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Hydrogen Cyanide Data

• Hazard Colorless to a pale blue gas, will
  explode, LEL 5.6
• Health extremely toxic, has a distinct taste
  resembling bitter almonds
• Exposures PEL/TWA 10ppm STEL N/A
  IDLH 50ppm
• Industries Leaching of precious metals, mining,
  chemical plants

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Effects of HCN

• 10ppm Permissible Exposure Limit
• 5-10ppm Headache, dizziness, unsteadiness
• 50-100ppm Feeling of suffocation, nausea
• 100-200ppm Death from exposure in 30 to 60
  minutes

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Nitric Oxide Data

• NO Colorless gas, typically formed when air is
  super heated and nitric compound like dynamite
  explode
• Hazards will not burn, will accelerate burning
• Health extremely toxic
• Exposure limit PEL/TWA 25ppm STEL N/A
  IDLH 100ppm
• Industries blasting, welding, and diesel
  combustion

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Effects of Various NO Levels

• 0-50ppm - Slight irritation of mucous
  membranes.
• 60-150ppm - Irritation is more intense, coughing
  and burning of the throat is evident, symptoms
  will clear if victim is removed quickly to clean
  air.
• 200ppm Dont go there!

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Summary

• Hazardous conditions can exist ANYWHERE and at
  ANYTIME
• Never trust your senses, always use a calibrated
  gas detection instrument Because
• It may very well Save your Life