STEL: 10ppm (Short Term exposure Limit - 15mins)
TWA: 5ppm (Time Weighted Average - 8hrs)
Rising Latching Alarms For Line Safety Applications
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Hydrogen Sulphide(H2S) is a colourless gas with a characteristic rotten eggs odour, it is also highly poisonous. Hydrogen Sulphide occurs naturally during plant and animal decay. Hydrogen Sulphide also occurs in volcanic gases. Hydrogen Sulphide will therefore naturally occur in landfill sites, bio-digesters, slurry pits, sewage treatment plants, sewers, some oil fields.
Hydrogen Sulphide is readily absorbed by the lungs, skin and eyes.
Exposure to high concentrations of hydrogen sulphide can have a severe effect on your health, effects may include collapse, inability to breathe and death within minutes. A range of effects on the nervous and cardiovascular system may occur following single or repeated exposures to high hydrogen sulphide concentrations. Skin discolouration, pain, itching, skin redness and local frostbite may occur if skin is exposed to compressed hydrogen sulphide liquid. Eye exposure may cause irritation, inflammation, tearing, sensitivity to light and conjunctivitis.
Unlike some other toxic materials it is not possible to build any resistance to Hydrogen Sulphide. Repeated exposures may make you more sensitive. Persons who have been drinking alcohol may be more sensitised to the effects of Hydrogen Sulphide poisoning.
- 0.47 ppb (Parts pr Billion) is the odour threshold, the point at which the human nose can detect and recognise H2S.
- 10 ppm is the OSHA permissible exposure limit (PEL) (8 hour time-weighted average).
- 10–20 ppm is the borderline concentration for eye irritation.
- 20 ppm is the acceptable ceiling concentration established by OSHA.
- 50 ppm is the acceptable maximum peak above the ceiling concentration for an 8-hour shift, with a maximum duration of 10 minutes.
- 50–100 ppm leads to eye damage.
- At 100–150 ppm your sense of smell (olfactory nerve) is paralysed after a few inhalations, and the sense of smell disappears, often together with awareness of danger.
- 320–530 ppm leads to pulmonary oedema with the possibility of death.
- 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.
- Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.
Hydrogen Sulphide is also very flammable with a Lower Explosive Limit of 4.3% by volume and is extremely corrosive.