Found this use of it interesting (from the Wikipedia article about dry ice): >Plumbers use equipment that forces pressurised liquid CO2 into a jacket around a

Found this use of it interesting (from the Wikipedia article about dry ice): >Plumbers use equipment that forces pressurised liquid CO2 into a jacket around a pipe. The dry ice formed causes the water to freeze, forming an ice plug, allowing them to perform repairs without turning off the water mains. This technique can be used on pipes up to 4 inches (100 mm) in diameter.[23]