H2S Safety course in Sargodha

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H2S Safety   course in Sargodha

H2S Safety course in Sargodha 

As indicated above, many metal ions react with hydrogen sulfide to give the corresponding metal sulfides. This conversion is widely exploited. For example, gases or waters contaminated by hydrogen sulfide can be cleaned with metals, by forming metal sulfides. In the purification of metal ores by flotation, mineral powders are often treated with hydrogen sulfide to enhance the separation. Metal parts are sometimes passivated with hydrogen sulfide. Catalysts used in hydrodesulfurization are routinely activated with hydrogen sulfide, and the behavior of metallic catalysts used in other parts of a refinery is also modified using hydrogen sulfide.

Hydrogen sulfide is a broad-spectrum poison, meaning that it can poison several different systems in the body, although the nervous system is most affected. The toxicity of H
2S is comparable with that of carbon monoxide.[42] It binds with iron in the mitochondrial cytochrome enzymes, thus preventing cellular respiration.

Since hydrogen sulfide occurs naturally in the body, the environment, and the gut, enzymes exist to detoxify it. At some threshold level, believed to average around 300–350 ppm, the oxidative enzymes become overwhelmed. Many personal safety gas detectors, such as those used by utility, sewage and petrochemical workers, are set to alarm at as low as 5 to 10 ppm and to go into high alarm at 15 ppm. Detoxification is effected by oxidation to sulfate, which is harmless.[43] Hence, low levels of hydrogen sulfide may be tolerated indefinitely.

Diagnostic of extreme poisoning by H
2S is the discolouration of copper coins in the pockets of the victim. Treatment involves immediate inhalation of amyl nitrite, injections of sodium nitrite, or administration of 4-dimethylaminophenol in combination with inhalation of pure oxygen, administration of bronchodilators to overcome eventual bronchospasm, and in some cases hyperbaric oxygen therapy (HBOT).[42] HBOT has clinical and anecdotal support.[44][45][46]

Exposure to lower concentrations can result in eye irritation, a sore throat and cough, nausea, shortness of breath, and fluid in the lungs (pulmonary edema).[42] These effects are believed to be due to the fact that hydrogen sulfide combines with alkali present in moist surface tissues to form sodium sulfide, a caustic.[47] These symptoms usually go away in a few weeks.

Long-term, low-level exposure may result in fatigue, loss of appetite, headaches, irritability, poor memory, and dizziness. Chronic exposure to low level H
2S (around 2 ppm) has been implicated in increased miscarriage and reproductive health issues among Russian and Finnish wood pulp workers,[48] but the reports have not (as of circa 1995) been replicated.

Short-term, high-level exposure can induce immediate collapse, with loss of breathing and a high probability of death. If death does not occur, high exposure to hydrogen sulfide can lead to cortical pseudolaminar necrosis, degeneration of the basal ganglia and cerebral edema.[42] Although respiratory paralysis may be immediate, it can also be delayed up to 72 hours.[49]

  • 0.00047 ppm or 0.47 ppb is the odor threshold, the point at which 50% of a human panel can detect the presence of an odor without being able to identify it.[50]
  • 10 ppm is the OSHA permissible exposure limit (PEL) (8 hour time-weighted average).[31]
  • 10–20 ppm is the borderline concentration for eye irritation.
  • 20 ppm is the acceptable ceiling concentration established by OSHA.[31]
  • 50 ppm is the acceptable maximum peak above the ceiling concentration for an 8-hour shift, with a maximum duration of 10 minutes.[31]
  • 50–100 ppm leads to eye damage.
  • At 100–150 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger.[51][52]
  • 320–530 ppm leads to pulmonary edema with the possibility of death.[42]
  • 530–1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing.
  • 800 ppm is the lethal concentration for 50% of humans for 5 minutes' exposure (LC50).
  • Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.
  • H2S Safety course in Sargodha