Occupational health and safety aspects in the handling of cryogenic materials

Cryogenic materials pose occupational health and safety hazards owing to their unique properties. They can cause severe cold burns on contact with unprotected body parts. Workplace safety may be breached as materials like epoxy/phenolic resins commonly used in laboratory bench-tops and sinks become brittle and fracture at low temperatures. Differential thermal contractions of the materials can cause equipment failure from thermal stresses. Large expansion ratio of most cryogenics on vaporization results into displacement and depletion of oxygen causing asphyxiation in poorly ventilated spaces. Vapor build-up of flammable cryogenic materials can cause fire or explosion. Improper venting and expansion may lead to over-pressurization of cryogenic equipment. Sudden gas release due to constant vaporization in warm surroundings may cause cryogenic container burst. Risk assessment consistent with Material-Safety-Data-Sheets (MSDS) and hazard analysis are essential to assess the potential dangers while using cryogenic materials. Indian Standard IS 5931 gives the Code of safety for handling cryogenic liquids. The storage, transport and handling should be according to the applicable standards. Administrative measures such as access control, training, check lists and engineering controls such as ventilation, gas detection systems, purging techniques are applied to deal with the cryogenic hazards. Effective Engineering controls of preventing product mix ups are achievable with standardized and product specific end connections. Personal protective equipments like cryogenic face-shields and gloves are available for protection from cryogenic hazards. Remedial measures after exposure may involve flushing affected area with tepid or cold water (if skin sticks to metal), non-stick dressing and medical intervention etc. (author)