SSAC liquid level control relays are used to control conductive liquid pumping operations using either floats or conductance probes. SymCom liquid level controls can be used in pump-up or pump-down applications. In either application, a probe is mounted at the desired tank level while a reference probe or common is mounted in the same manner for nonconductive tanks, or attached to a conductive tank. When ABB liquid level control senses a change in the resistance between the probe and reference probe/common it will change state and either fill or drain the tank depending on the specified application. Littelfuse liquid level relays provide differential level control for pumping applications using either floats or conductance probes. SSAC liquid level controls are designed for both pump-up and pump-down systems. SSAC designs and manufactures electronic controls for original equipment manufacturers, for process control and automation designers; obstruction lighting control designers; and for a large group of industrial customers and service contractors.