To limit the probability that escaped liquid will enter a building through the window opening, which could lead to the spread of liquid inside the building, which could lead to the ignition of vapour from a nearby ignition source, which could lead to harm to persons inside the building.
To limit the probability that the piping will be exposed to a fire originating inside the building, which could lead to the failure of the piping, which could lead to the escape of liquid, which could lead to the ignition of vapour from a nearby ignition source, which could lead to harm to persons.