What is a conductivity probe used for in a tank?

• A. In a conductive liquid, to measure a tank level.
• B. To measure tank temperature.
• C. To measure tank pressure.
• D. To measure flow rate in the pipe.

Answer: (A)

A conductivity probe in a tank is used to sense the presence of a conductive liquid to determine the liquid level. The probe works by applying a signal between electrodes; when the probe is immersed in a conductive liquid, ions in the liquid allow current to flow, closing the circuit and indicating that the level has reached that depth. If the liquid level falls away from the probe, air is an insulator and the circuit opens, signaling a lower level. This method relies on the liquid’s conductivity, so it’s suitable only for conductive liquids. It’s not used to measure temperature, pressure, or flow rate, which require other types of sensors.