What type of devices is used to control the start and stop functions of pumps?

The correct choice is devices such as floats because they are specifically designed to detect the level of liquid in a tank or well. When the liquid level rises to a certain point, the float activates a switch that can start or stop a pump, ensuring that the pump operates only when needed to maintain appropriate liquid levels. This automatic control helps prevent overflow or dry running of the pump, which can cause damage.

While switches can also be used to control pump operations, they typically require manual intervention unless combined with other sensing technologies. Timers can set predetermined intervals for when a pump should operate but do not respond to real-time conditions, making them less effective for immediate control needs. Pressure gauges measure the pressure of fluids but do not directly control pumps; they inform operators about system conditions rather than functioning as control devices themselves.