To limit the probability of delays in shutting off the flow of liquid in a fire, which could lead to the escape of liquid not being minimized, which could lead to the spread of fire, which could lead to harm to persons.
To limit the probability of delays in shutting off the flow of liquid in a liquid spill situation, which could lead to the spread of liquid, which could lead to the ignition of vapour from a nearby ignition source, which could lead to harm to persons.