Because of its heat carrying capabilities, steam is used for heating purposes. Under confinement, as steam is heated above its boiling point, its pressure increases. Therefore, steam carrying pipes and radiators must be able to hold great pressures. Whenever these systems fail, disaster looms, usually in the form of an explosion. Because of this danger, steam heating has largely been replaced by hot water and heated air heating systems. Steam is by far the most efficient, but its risk seems not acceptable. Steam under pressure also has another use, as it has an incredible ability to penetrate porous material.
Pressure cookers are an example of steam being used in this manner. Under pressure steam penetrates deep into food, carrying its heat and cooking quickly and efficiently. A safety feature of pressure cookers are built in pressure relief valves. These release excess steam pressure from confinement and into the air. Despite warnings to keep this valve clear, dangerous explosions have occurred when it gets blocked. Kitchens have seen metal cookers turned in shrapnel that has killed the cook. For this reason, many have abandoned pressure cooking using steam pressure.
Another use of steam’s penetrating abilities are found when working with fibrous materials. Wood for example is subjected to steam to help it absorb moisture making it more pliable. Various wooden products use steam to make them bendable. After being held in a bended state and dried, wood retains the bent shape. Common examples of this are found in boats, furniture and curved building frame construction. Another fibrous material commonly subjected to steam is cloth. Steam ironing is the example. Here, again, steam brings moisture deep into the fibers rendering them pliable. Pressure from the iron flattens the fibers and cloth and when dried they retain their flattened shape.
In nature, steam exists under tremendous pressure deep in the bowels of the earth. Water meeting earth’s molten core, renders it into steam. Because it is deep in the earth this steam is held under incredible pressure as it absorbs more and more heat. These steam pockets are called superheated. In some places, Iceland for example, these deep steam pockets naturally vent near the surface. This occurrence is used for heating purposes and gives an inexpensive source of energy. In other places where natural vents do not occur near the surface, pipes are drilled down to steam pockets. These deep troves of steam come to the surface and its pressure used to drive electricity generating turbines. As its pressure and heat is dissipated this steam returns to its liquid state and often is used for irrigation. For this reason, many steam exploratory projects are sited in arid locals.
Whether natural or man made, fires are constantly tended to produce this cycle of water being taken from its liquid state to gaseous and back to liquid. Water is not the only liquid that is brought to its boiling point turned into a gas and its properties changed before it is condensed back into its liquid form. Most liquids have a volatile gaseous state and heat properties are a constant part of this equation. Therefore fires of some sort are integral to our physical nature.