An improved liquid oxygen breathing apparatus, weighing 33 lb (15 kg) and approved for use in British mines. Air is fed to the wearer at a temperature of 50 degrees F (10 degrees C) rising to 70 degrees F (21.1 degrees C) in just over 1/2 h and is still only 80 degrees F (26.7 degrees C) after 2-1/2 h.