All about Hydrogen Sulphide..

What is Hydrogen Sulphide?

Also known as H2S (not to be mistaken for the new Rail Link HS2!), this gas has various other names such as; sewer gas, swamp gas, stink damp, and sour damps. It is colourless and is known for its rotten egg smell. Hydrogen Sulphide isn’t only found in Oil Refineries but in other locations too, such as; farms, fuel depots, deep drainage, and anywhere where water may remain stagnant. This is not only due to man-made industries but is also from naturally occurring phenomena. For example, off the coast of Namibia in Africa, a Hydrogen Sulphide bloom, 150km in length, was detected in the sea.

Affected Legislation Includes:

HASAW1974

COSHH 2002 Regulations

DSEAR 2002 Regulations

MHSWR1999

 

Summary

In higher concentrations, exposure to this gas can lead to paralysis and, eventually, death. Perhaps the most cruel aspect of this gas is its ability to kill off the victim’s sense of smell in concentrations of over 60ppm (parts per million). While working in the Petroleum Industry, the smell was constantly there as the low odour of rotten eggs. This gas is also flammable in certain ranges of concentration, so specialist equipment is needed when operating in areas contaminated with this gas. The gas is also heavier than air, so this may be present at the bottom of deep excavations or opened deep drainage. Like Lemmings, multiple fatalities have been known for people going in to rescue others who’ve collapsed at the base of an excavation. Training for casualty extraction in confined spaces is essential to prevent this.

An Employer should be reasonably expected to know that a risk of Hydrogen Sulphide is possible due to their work activities. Therefore it would be reasonable to protect their workers in line with Section 2 of the Health & Safety at Work Act etc 1974.

 

Proactive measures include

  • ensuring adequate containment of vessels

  • burn off gas (which produces Sulphur Dioxide)

  • Release into atmosphere

  • Intrinsically safe equipment (equipment that will not create a spark)

 

Reactive measures include

  • RPE (Respiratory Protective Equipment)

  • EEBD (Emergency Escape Breathing Devices)

  • Windsocks for wind direction

  • Static Air monitoring

  • Personal Gas Meter

 

Sidenote: This gas was used by the British military in World War 1 as a chemical weapon, but it was not ideal due to its pungent smell and flammability.

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