Nguy hiểm H2S

Crowcon Blog#6: H2S: Toxic and Deadly – Chris Explains More About This Toxic Gas

Many of you have met hydrogen sulphide (H2S). If you have ever smashed a rotten egg, its peculiar smell is H2S.

H2S is a toxic gas found in many working environments, and even at low concentrations it is poisonous. It can be created from human products or by the decomposition of by-products in nature. From offshore oil production to drainage works, petrochemical plants to farms and fishing vessels, H2S is a real danger to workers.

Dangers of not measuring H2S toxic gases
Dangers of not measuring H2S toxic gas concentrations

Artificial Products

Hydrogen sulfide is a by-product of processes, such as oil refining, mining, paper plants, and iron metallurgy. It usually appears during the filtration of crude oil and the treatment of natural gas. With the growing demand for oil and gas, oil wells that may not have been exploited before because they are too sour are being marketed. This led to increasing difficulty controlling the level of sulfur in the finished product, so it was necessary to invest large amounts of money in these methods of neutralizing dangerous gases from hydrocarbon energy sources.


Hydrogen sulfide is also a common by-product of the biodegradation of organic matter, due to the action of bacteria. In low-oxygen or oxygen-free environments, these bacteria use sulfur instead of oxygen to generate energy. It “oxidizes” organic matter, produces H2S. These airbags can be gathered in enclosed spaces or accumulate in the material itself, and it will release when affected.

Workers in sewerage and sewerage systems and pipelines may be exposed to excessively high concentrations of H2S and have deadly consequences. Farmers are often not aware of the risks of going into inspections in empty tanks without using gas detectors. There may have been mud cleaning in which gas remained.

Fishermen are also at risk. Improperly preserved and refrigerated fish can pose a danger to fishermen on board. There is also a danger from H2S in ballast water and sewage tanks of vessels; An incident occurred when the crew members on the high-end ship may have been in a coma by H2S while carrying out repairs to some of the duc ducs in the ship’s engine room.

How dangerous is H2S?

Hydrogen sulfide is volatile at high concentrations. However, the main danger is carbon monoxide, it is very toxic. It inhibits respiratory cells and oxygen absorption. Prolonged exposure to 2-5 parts per million (ppm) of H2S can cause nausea and headaches and tearing. At 20ppm, symptoms include fatigue, headache, discomfort, dizziness and memory loss. More severe when there are symptoms of cough, conjunctivitis, nerve paralysis (loss of smell), collapse and rapid unconsciousness. Exposure at higher levels can lead to almost immediate death.

As a toxic gas, H2S can have an immediate effect, and long-term exposure can cause chronic disease or even death. As a result, many display devices will have both instant alarms and TWA (Time-Weighted Average).

H2S is heavier than air, it sinks to the floor and can accumulate in shafts, grooves of floor pipes. Initially there will be a rotten egg smell, the stench of H2S is very noticeable. However, it quickly loses your sense of smell, creating a false sense of gas that has spread. Without knowing about the potential danger, someone can continue to work and take no appropriate precautions against the risk of intoxication.

Types of gas detectors

Both handheld and fixed detectors can be used to monitor H2S. Fixed systems usually consist of one or more probes connected to a separate panel. If the detector reports a hazardous gas level, the control panel will alert and activate the external siren and indicator light.

Typically, a compact handheld toxic gas concentration meter to monitor contact time is more suitable. Combining one or more sensors (if there may be additional hazards) with strong light and sound signals to alert when the alarm gas level is set in the machine, handheld detectors can be carried with them or hung wherever they need to. In addition, the handheld air detector is a compact instrument that is easily carried in a narrow space to ensure that it does not ignore places where there may be high concentrations of toxic gases.

Trans by Mr. Manh # TESIN VIETNAM

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