Massachusetts 2nd Class Fireman's Practice Exam

The factor of evaporation is a term used in steam calculations to express the efficiency with which water is converted into steam in a boiler. It is defined specifically as the amount of heat added to the boiler, expressed in British thermal units (Btu), divided by a standard benchmark value, which is 970.3 Btu. This number represents the energy required to convert one pound of water at 212°F (the boiling point) into steam at the same temperature.

By standardizing the conversion in this way, it allows for easier comparison and calculation of steam-producing capacity under varying conditions. The specific value of 970.3 Btu is derived from the heat required to convert water to steam at the boiling point, making it a practical reference point for engineers and firemen in assessing boiler performance.

Options that present alternative formulations or figures do not correctly capture the essence of the factor of evaporation as defined in this context. Thus, analyzing the heat in terms of the specific conversion factor directly tied to the steam production clarifies and verifies the importance of the correct formulation.