What marking must be indicated in pounds on a cylinder?

The correct answer pertains to the marking that must be indicated on a cylinder, which is the water capacity. This is a critical specification because it provides information on the volume of water that the cylinder can hold at full capacity, which correlates to the amount of liquefied petroleum gas (LPG) it can safely contain. The water capacity is indicated in pounds and plays a crucial role in ensuring the proper filling of the cylinder; it allows users to calculate the maximum amount of LPG that can be filled without exceeding safe operating conditions.

Understanding the water capacity is essential for safely handling and using propane cylinders, as it informs users of the cylinder's size, influencing storage, transportation, and safety practices. Accurate markings contribute to compliance with safety regulations and help prevent overfilling, which could lead to dangerous situations such as leaks or explosions.