What is the purpose of a float switch in pump control systems?

A float switch is an essential component in pump control systems specifically designed to monitor the water level in a tank or reservoir. Its primary function is to automatically turn the pump on or off, responding to varying water levels. As the water level rises or falls, the float attached to the switch moves accordingly. When the water reaches a pre-determined level, the float activates the switch, which then initiates the pumping process to either fill the tank or drain excess water. This automation helps maintain the desired water level, prevents overflow, and protects the pump from running dry, which could lead to damage.

In contrast, the other options describe functionalities that are not within the capabilities of a float switch. Maintaining a constant temperature in a tank involves different types of control mechanisms, such as thermostats or heating elements. Regulating fluid viscosity is associated with chemical processes or adjustments in temperature and pressure, not with a simple float switch. Similarly, measuring flow rate involves flow meters designed to track the velocity or quantity of liquid passing through a point, something that is distinctly separate from the role of a float switch in water level management.