A 3-element feedwater regulator measures the steam flow and the flow of what into the boiler?

The 3-element feedwater regulator is designed to maintain the water level in a steam boiler by continuously monitoring and adjusting the flow of feedwater into the boiler. It typically measures three elements: the steam flow leaving the boiler, the water level in the boiler, and the feedwater flow entering the boiler.

By regulating the feedwater, the system ensures that there is always enough water to produce steam without risking the boiler running dry or experiencing surges in water level. This is crucial for safe and efficient boiler operation, as maintaining the proper water level is essential to prevent overheating and potential damage.

The other options, such as gas, electricity, and fuel, do not pertain to the function of the 3-element feedwater regulator. Gas and fuel relate to the combustion process in a boiler, while electricity is relevant to powering various controls and components but does not directly connect to the regulating of water flow. Therefore, the correct answer, which focuses on the flow of feedwater, accurately reflects the primary function of the regulator within a steam system.