Born in Berlin, Hans Epstein was educated in Switzerland and Bavaria, obtaining his PhD in 1934 with highest honours. Leaving Germany to escape Nazi persecution he secured an appointment in the Clarendon Laboratory, Oxford, where, at the suggestion of Robert Macintosh, he worked on the design of more reliable anaesthetic inhalers.

At the outbreak of war in 1939 Epstein joined the Nuffield Anaesthetics Department and was set to design simple portable apparatuses for field conditions. The result was the Oxford Vaporizer, which made use of the latent heat of fusion of calcium chloride crystals to maintain a constant vapour concentration. Nuffield’s car factory in Oxford manufactured some 3,000, which were used in all campaigns. Epstein designed other vaporizers, to which his name or initial is often attached; the Emotril for obstetric analgesia, the EMO, and the Oxford miniature vaporizer.

Epstein also participated in the experiments in which Edgar Pask was the subject on the design of a safe life-jacket, and in studies on oxygen tension in airmen at varying altitudes. He was co-author of the textbook Physics for the Anaesthetist, which went through four editions, and he taught and lectured widely until his death, aged 93.