Final answer:
Gases Under Pressure signify potential hazards due to the high pressure at which gases are stored in cylinders. These cylinders need careful handling and proper temperature control to avoid safety risks. Gas law principles are utilized to ensure cylinder safety and prevent accidents such as rupture or explosion.
Step-by-step explanation:
The Gas Cylinder pictogram represents a hazard from Gases Under Pressure. It indicates that gas is stored at a potentially dangerous high pressure and may pose safety risks if not handled properly. For example, a gas cylinder stored at room temperature might be pressurized to about 200 atmospheres, with a safety factor of 2, implying that it likely will not fail unless the pressure reaches nearly 400 atmospheres.
However, if exposed to fire, the heat can cause the internal pressure to increase, which may result in cylinder failure if the pressure exceeds the safety threshold.
Understanding the behavior of gases under pressure also involves the principles of gas laws. In the case where an adjustable piston is used to modify the volume of a gas-filled cylinder, the pressure will inversely change according to Boyle's Law; reducing the volume while keeping the temperature constant will double the pressure.
Conversely, increasing the volume at constant temperature will see a decrease in pressure. This principle is a critical aspect of safety, as seen with warnings on gas cans which may state to store below certain temperatures to prevent pressure build-up due to increased temperature from leading to explosion or rupture.
In practical situations, such as in the manufacturing of gas cylinders, safety against sudden rupture is paramount, especially when containing hazardous gases like chlorine.
The ideal gas law and the van der Waals equation can be utilized to determine if a cylinder is likely to be safe at a specified temperature, ensuring that the pressure does not exceed the rupture pressure of the cylinder.