Hydrogen sulfide: H₂S

What is Hydrogen sulphide?

It is an extremely toxic natural gas, exposure at high concentration can kill you. Hydrogen sulphide is the chemical compound with the
formula H₂S.

Hydrogen Sulphide is created naturally by decaying organic matter and is released from sewage sludge, liquid manure, and sulphur hot springs. It is formed when Sulphur is removed from petroleum products in the petroleum refining process and is a by-product of paper pulping

Other names of H₂S:

- Hydrogen Sulphide

- Rotten Egg Gas

- Stink Damp

- Sour Gas

- Hydro Sulfuric acid

- Dihydrogen Sulphide

- Sulfurated Hydrogen


H₂S HAZARDS and health effects:

• Nausea

• Cough

• Irritation

• Difficult breathing

• Moderate headache

• Dizziness

• Tightness of chest

• Death

• Failure of the respiratory system

• Lungs problem

• Eye, brain, respiratory control system

Control measure:

1.    Personal escape set

2.    Continuous gas monitoring

3.    Clean Shave

4.    Buddy system

5.    Location of the assembly point

6.    Emergency vehicle

7.    The emergency number must be displayed

8.    Escape routes

9.    Windsock

10.    Competent staff

11.    E.P.T.W, T.R.A.

12.    Training for escape or rescue in case of H₂S Leak.


Beware! Acute effects can follow one breath of H₂S subjected to physical susceptibility of the individual.


How to mitigate the potential risk? (Not limited to);

1)    Reducing risk by Gas Testing.

2)    Providing monitoring of an area to ensure the continued safety of a workplace by
continual Gas Testing.

3) Don't grant a permit to work alone in H₂S prone area.

4)    Avoid drinks and food consumption during work at H₂S prone area.

5) Don't stay in H₂S area if there is no work.

6)    Keep escape mask while entering and working in H₂S prone area.

7)    A trained person should be deployed to work in H₂S area.

8) Don't try to find any source of the leak without SCBA.

9)    Provide barricade and Caution signage to restrict unauthorized entry to the hazardous

10)    Provide and train the workmen to use Personal gas detectors in H₂S prone area.

11)    Check wind sock location before entering H₂S area.

12)    Use SCBA for H₂S exposure more than T.L.V.

13) Don't involve in rescue unless you are adequately trained if incompetent leave the situation to the experts. Never run to become a HERO.

In high quantities, you may never smell H₂S at all. Do not rely on your nose to aid in detecting the presence of Hydrogen Sulphide gas.

A good guideline in dealing with H₂S is, NEVER to TRUST YOUR SENSES.

Type of P.P.E.'s that are needed to work in H₂S environment:

•    Emergency Escape Breathing Apparatus

•    Gas Monitor

•    Masks: Type of masks:

1. A.P.R.: Air-purifying respirator (clean air supply to the user) (Emergency Escape Breathing Apparatus)

2. A.S.R.: Air supplied respirator (continuous or as fixed air supply to the user)


What to do in H₂S leak?


• Never let a victim of H₂S drink water (H₂S + Plus becomes into acid). Don't go inside a H₂S
zone to save anyone unless you are equipped with SCBA and trained for the
rescue activities.

• All that we can do is call Immediately for help.

• If there is a H₂S leak then don't try to ignite any vehicle, a spark can easily ignite a fire.

Hydrogen Sulphide, which is mostly present in the oils and gas sectors. It's a dangerous gas that can knock out our sense of smell and attack our nervous system and make one unconscious.

If your premises have H₂S presence, make sure all the workmen have undergone the training of basic H₂S and the evacuation method.
Make sure they understand and asked questions about the comprehensibility, as, without proper training, there is no way of escaping this one.

Always remember only the individuals who have undergone proper training can attempt rescue operation and that too with appropriate P.P.E.

H₂S Emergency procedure:

• Stop work immediately.

• Hold your breath.

• Wear Emergency Escape Breathing Apparatus (EEBA).

• Switch off your power tools and secure.

• To move fast towards assembly point.

• Follow crosswind then upwind direction.

• Inform a second person to advise the proposed action.

• To inform the immediate supervisor.

• The responsible supervisor will conduct head counting.

• Plant operator will be notified. If not available dial emergency number and explain (Don't panic while defining the emergency).

- Name & I/D No,

- Location of emergency,

- Type of emergency,

- Listen what they instruct, keenly

• Don't re-enter the area before ensuring that the hazard is eliminated completely. It will be de cleared by Plant operator/ Safety officer and site Supervisor.

• Proceed to a safe assembly area. Walk swiftly (don't run) & wait for further instructions, head counting.

• Keep the corridor and stairs clear (remove obstruction).

• All work permits are suspended during an emergency.


Health effects of Hydrogen Sulphide Exposure:


Reference: Info-graphic is taken from H2S – The Killer from the Alberta Government

A small illustration of Hydrogen Sulphide (H₂S):

•    H₂S is an extremely toxic gas that is colourless, flammable, heavier than air, soluble
and has the smell of rotten eggs at lower concentration levels. Hydrogen Sulphide is one of the Deadliest natural gases known to mankind; it is the product of decomposition of organic matter by bacteria and is measured in parts per million (P.P.M.).

•    At smaller quantity, one can smell the leak, but never rely on the scenes as at higher
levels one's sense of smell gets knocked off.

•    The main activities associated with H₂S exposure are Tank Gauging, Maintenance
operation, Pipeline and plumb repair, Confined space entry and Unclogging drains.

•    Hydrogen sulphide, it is highly toxic, colourless, deadly, odourless & highly flammable 4.3% (43.000 PPM – 46% (460.000 PPM) gases which produced and generated by decomposition of organic materials. Found in the oil industry include drainage water, particularly sea water.

• 19% Heavier than air (1.87 vapour density).

•    H₂S entered the body through the lungs. It dissolved readily in blood & carried by the
bloodstream throughout the body. It affects breathing by causing the respiratory control centre in the brain to shut down without message from the brain respiration stops, death occurs because the oxygen in the blood is quickly used up causing the heart to stop which leads to death.

• Auto ignites at a temperature of 500°f (260°c).

•    Highly soluble in water & liquid hydrocarbons at elevated pressures & will involve as a
gas from the liquid state at ambient conditions.

• It burns with a blue flame & when burned produces sulphur dioxide(so2) another toxic gas.

•    It is highly corrosive to metal & can lead to hydrogen embrittlement & sulphide
stress cracking of unlined or untreated metals or their alloys.

• Molecular weight: 34.08 gm.

Questions and Answers

Question: How does H₂S enter the body?

Answer: Much smaller amounts can enter your body through the skin. Hydrogen sulphide is a gas, so you would not likely be exposed to it by ingestion. When you breathe air containing hydrogen sulphide or when hydrogen sulphide comes into contact with skin, it goes into the bloodstream and distributed throughout the body


Question: What is suitable P.P.M. for H₂S to work with safety?

Answer: ANSI standard of safe working practices with H₂S Z 390.1 stipulates of safe working practices with H₂S should not touch 10 ppm.

OSHA sets T.L.V. as 10 Ppm.

Question: Are there really no uses of Hydrogen sulphide?
After all, all we hear is, how dangerous it is.

Answer:  As once said by a wise man,

"Nothing is useless, its how we see it and use it will justify its purpose".

H₂S is used primarily in the production of Sulphur and
sulfuric acid. It can also be used to make other chemicals such as sodium
sulphide and sodium hydrosulphide, which are widely used to create a variety of
products, including dyes, pesticides, and pharmaceuticals. Hydrogen sulphide is
utilized in the purification of nickel and manganese as well as hydrochloric
and sulfuric acids. It is used in metallurgy, the nuclear industry, and in
laboratory experiments. It is also used as an agricultural disinfectant.


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