Frozen liquid oxygen: In some cases people do not connect their stroller (mobile liquid oxygen device) properly to its main unit. As liquid oxygen in the main tank has a freezing point of 50.5 K (−368.77 °F; −222.65 °C) it could, when one tries to fill up their stroller freeze the valves partly. The result will be that the reservoirs will stay connected due to the ice framing or that the valves of either or one does not close properly and oxygen is leaking out of the tank through those valves. One can solve these problems by covering the valves with luke warm water to set them loose and or close the valves.