The cells on our Cato (Tiny Button type cell) Anaesthetic machines are most unreliable, life spans of days to a max. of about 6 weeks being the norm. Due to this however in most cases we are given replacements FOC....They also say that they (Drager) don't have this problem in any other location, which seems to be a standard statement from most equipment suppliers re. any technical problem for which no fix has been found. Theatres are difficult areas though as gases can be left flowing reducing the life span of O2 cells.