What is the function of the feedwater regulator?

The function of the feedwater regulator is to control the flow of water into the boiler. This component plays a critical role in maintaining the proper water level within the boiler system. By regulating how much feedwater enters the boiler, the feedwater regulator ensures that the boiler maintains the necessary amount of water for efficient operation. This is essential to prevent issues such as overheating or damage caused by low water levels, which can lead to unsafe operating conditions.

The other options address different aspects of boiler operation: measuring temperature, regulating pressure, and analyzing water quality, but they do not pertain to the specific role of the feedwater regulator. This focus on controlling the water supply is fundamental to the functionality and safety of the boiler system, which is why it is the correct answer.