Which device is used to start a sewage ejector pump when water reaches a certain level?

• A. Float switch
• B. Pressure relief valve
• C. Solenoid valve
• D. Bimetal switch

Answer: (A)

The concept here is automatic level sensing to control a pump. A float switch sits in the sump and rises with the water. When the water reaches the set level, the float moves to activate an electrical circuit that starts the sewage ejector pump. As the water level drops, the float lowers and opens the circuit, stopping the pump. This provides automatic on/off operation to prevent overflow and keep wastewater moving.

Other devices don’t fit this purpose: a pressure relief valve protects against high pressure in pipes, not water level; a solenoid valve controls flow through a valve using an electric coil but isn’t inherently a level sensor; a bimetal switch reacts to temperature changes, not liquid level.