A member has reported a near miss incident in which a fire extinguisher failed due to corrosion of the internal stem. The failure was discovered during inspections of fire extinguishers during a mobilisation. Corrosion had taken place where the brass fitting connected to the aluminium stem. The extinguisher was relatively new and this was its first inspection. On removal of the pillar valve, the technician noticed an unusual amount of corrosion around the internal female brass fitting connecting the aluminium stem to the internal male thread of the pillar valve. The technician touched the stem and it fell apart at the corroded area. The internal inspection of the cylinder found that it was in good condition with no signs of corrosion.
Members are reminded of the corrosion potential with dissimilar metals, particularly in the case of pressure vessels. Our member notes that had the fire extinguisher been required for use in a hyperbaric chamber all that would have happened would have been a release of gas when operated. Our member is in direct contact with the supplier to try and resolve the issue.