A survival stove is fed with propane vapour from a cylinder containing an equilibrium liquid/vapour mixture. The vapour is fed through the small-bore pipe before entering the burner where it is mixed with atmospheric air and burnt at atmospheric pressure namely 1058 mbar. If the pressure drop through the pipework and burner is 75 mbar, what is the minimum temperature at which the gas cylinder may be stored if a flow of propane is to be maintained to the burner.