What is the primary function of an electric float switch in a flooded shell-and-tube cooler?

The primary function of an electric float switch in a flooded shell-and-tube cooler is to control the flow of refrigerant into the shell. This device plays a critical role in maintaining the proper level of refrigerant within the cooler and ensuring efficient heat transfer between the refrigerant and the brine in the tubes.

When the refrigerant level rises above a certain point, the float switch activates to close or open a valve accordingly, preventing overflow and maintaining optimal operational efficiency. This control ensures that the shell side of the cooler remains adequately flooded for effective heat exchange, which is essential for the overall cooling process.

The other options, while related to different aspects of operational procedures in such systems, do not define the float switch's primary role. Although controlling brine flow and purging oils or noncondensable gases are crucial maintenance tasks, they are not directly managed by the float switch, which is focused specifically on the refrigerant management within the cooler.