Level switches (AKA float switch) are activated by liquid levels, such as in toilet tanks, sump pumps and in processing plants. When the liquid in tank reaches a certain level, a float rises. An arm on the float throws a switch when the liquid reaches a predetermined level. The switch may actuate a valve that cuts off the flow of liquid into the tank, or it may actuate some other process such as activating a pump. Similarly a flow switch is a mechanical device which controls flows (usually of liquid, but sometimes for air or steam) by sending a trip signal to an actuator which operates a pump or valve. Level switches are a type of both pump controls and level sensors.