Water is heated in a high pressure cooker, until the highest possible pressure is reached. The valve is then opened, allowing the pressurised steam to travel down a hose and into a hot water bottle. The hot water bottle expands under the pressure, growing in size until it is around 50 cm wide. Suddenly, it explodes with a loud bang.
How does it work?
The secure seal on the pressure cooker allows a temperature of around 120°C to be reached with a pressure of approximately 2 bar. Opening the valve releases a large amount of steam very quickly, which in this case travels into the hot water bottle and inflates it. Eventually the hot water bottle can withstand no more pressure and is forced to rip open with a loud bang.
This experiment illustrates the enormous power that can be harnessed from steam engines.
Safety Tips
The layout of the stage should allow for a suitably large gap between the hot water bottle and the audience. A net should also be set up in front of the water bottle. The explosion releases large amounts of steam, which may interfere with smoke detectors in the building.
