BS 8478:2011

BS 8478:2011 specifies requirements and test methods for the composition and purity of breathing gases for use in diving and hyperbaric applications.

The toxic and harmful effects of impurities in breathing gases are increased at hyperbaric applications therefore the limiting number of impurities has been reduced appropriately to allow for this effect.

This standard is applicable to the following categories of breathing gas mixtures:

• breathing oxygen
• oxygen compatible air
• nitrogen depleted air
• oxygen and nitrogen gas mixtures
• oxygen and helium gas mixtures
• oxygen, helium and nitrogen gas mixtures

Please note that compressed air for breathing apparatus is specified in the BS EN 12021.

• The requirements for the composition of oxygen compatible air and the composition of nitrogen depleted air have been added
• The requirements for the composition of helium for making breathing gas mixtures has been added
• The requirements for the mixing of gases have been added
• The requirements for the mixing of gases have been added
• The requirements for the freedom from particulate contamination are no longer specified
• The maximum permissible water content in breathing oxygen , oxygen and nitrogen gas mixtures, oxygen and helium gas mixtures and oxygen, helium and nitrogen gas mixtures have been raised
• For oxygen and helium gas mixtures, the maximum carbon monoxide content has been reduced and the maximum content of “other non-toxic gases” has been reduced
• The sampling methods have been changed
• The test method for oil content has been changed
• Methods have been added for stain detector tube and stain system analysis.

• BS EN 1089-3, Transportable gas cylinders - Gas Cylinder identification (excluding LPG) - Part 3: Colour Coding

• BS EN ISO 13769, Gas cylinders - Precautionary labels

• BS ISO 8573-2 Compressed air - Part 2: Test methods for oil and aerosol content
• HEALTH AND SAFETY EXECUTIVE. Workplace exposure limits. Guidance Note EH 40.

• HEALTH AND SAFETY EXECUTIVE. Occupational exposure limits for hyperbaric conditions. Hazard Assessment Document EH 75/2