Tuesday, November 3, 2020

Hydrogen Sulfide (H2S)

Gas Hazards:

  1. Gas exposure
  2. Poisoning
  3. Gas fire
  4. Gas explosion
  5. Gas asphyxiation / suffocation

Control Measure:

  1. TPC Training
  2. PGM
  3. Personal escape set
  4. Continuous gas monitoring
  5. Clean shave
  6. Buddy system
  7. Location of assembly point
  8. Emergency vehicle
  9. Emergency no. displayed
  10. Escape routes
  11. Wind sock
  12. EPTW, TRA, MS

Hydrogen Sulfide (H2S): 

  1. Hydrogen sulfide (H2S), it is Extremely toxic, color less, deadly, odor less & highly flammable 4.3% (43.000 PPM – 46% (460.000 PPM) gases which produced and generated by decomposition of organic materials. Found in oil industry include of drainage water basically sea water
  2. 19’/. Heavier than air (1.87 vapor density)
  3. Auto ignite at temperature of 518’f (260’c U.A. E) (232’c in Qatar)  
  4. Molecular weight: 34.08 gm
  5. H2S boiling point: 60.7-degree c’
  6. SO2 boiling point: 10-degree c’
  7. S (Sulphur) boiling point: 444.6-degree c’
  8. Inhale 20% o2 and the air
  9. Exhale 15% o2 so 5% volume of air consumed in each breath & converted to co2
  10. Human uses 550 liters pure o2 (19 cubic feet) per day
  11. Tree produce 260 pounds of o2 per year
  12. 1-minute approx. 12- breath taking by adult
  13. Nicotine gas used in cigarette


H2S is highly soluble gas which dissolves easily in water, oil & most liquid hydrocarbons & creates a weak sulphuric acid with changes in temperature & pressure. The solubility decreases & gas is released back in the environment.


H2S is corrosive & forms iron Sulphide (FES2) scales on carbon steel. This product is often found in vessels & pipes contain H2S by weakening the carbon steel. It makes the metal brittle & breaks easily

Effects of Exposure: 

2-categories, Internal exposure e.g. breathing and external exposure can irritate eye & skin can minimize by use of PPE’s and precautions e.g. washing affected area 

The degree of adverse response to exposure depends of 4 factors: DFIS

  1. Duration (of exposure): the length of time individual is exposed
  2. Frequency (of exposure): how often has the individual been exposed within a working day
  3. Intensity: how much doses the individual employee/worker is exposed to within a working day?
  4. Susceptibility: the individual physiological made of.
  5. The consumption of alcohol during the 24 hours prior to exposure to H2S will make the subject more susceptible to adverse reaction even at low level of concentration. Don’t mix alcohol & H2S the result could be catastrophic
  6. Individuals with an asthmatic condition are also more vulnerable

Symptom & Effect of H2S:

  1. Less than 1 PPM: smell like rotten egg 0.1-100PPM
  2. 10 PPM: 8 hours’ average value, No known adverse health effect.  40 Hrs. a week
  3. 15 PPM: 15 minutes work 1-hour rest in full day 1 hour only 15 x 4=1 hour
  4. 30 PPM eye & respiratory tract irritation
  5. 50 PPM eye irritation &coughing
  6. 100 PPM (IDLH) loss of sense of smell (3 - 15 minutes)
  7. 500 PPM dizziness, headache, nausea, abdomen pains within 15 minutes, loss of consciousness & possibility death after 30 minutes of exposure. If effective resuscitation not applied
  8. 800 PPM Death 1 to 4 minutes
  9. 1000 PPM & above, Rapid unconsciousness followed by death within minutes after single inhale
  10. More symptoms of low levels of exposure or continues, prolonged. Skin irritation, Irrational behavior, Fatigue, Coughing, Dryness in nose & throat, Loss of appetite 


100f’ – 32 divided by 1.8=37.77 c’


37.77c’ x 1.8 + 32=100f’ 

  1. 1 PPM = 1 mm in 1 kilometer
  2. 1 ppm=1mg per litre (mg/pl)
  3. CO2 in minus temperature at 66’c holds the hose not nozzle possible cold burn
  4. Oxygen (O2) no explosion of a methane air mixture. Can occur/happen at 12 percent.
  5. Gravity of oxygen 1.105%
  6. Gravity of hydrogen (H2) 0.0695 %
  7. H2S boiling point: 60.7-degree c’
  8. SO2 boiling point: 10-degree c’
  9. S (Sulphur) boiling point: 444.6-degree c’
  10. Flammable: below 100 Fahrenheit temperature (ignition 37,77 c’)
  11. Combustible: above 100 Fahrenheit temperature (ignition 37,77 c’)

Direction of Air: 

  1. Wind Socks,
  2. Streamer, 
  3. Flags, 
  4. Sand in hands, 
  5. Smoke from the flare stack
  6. Hand kerchief

Type of SCBA:

  1. Open circuit: which going to outside ex-held air
  2. Close circuit: not go to outside, recycle & giving it back to wearer. Only 4% co2 going outside

Type of Mask:

  1. Air Purifying Respirator (Clean Air Supply to User-APR)
  2. Air Supplied Respirator (Continuous or as fixed air supply to user-ASR)

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