Which of the following is a valid level measurement transmitter listed in the material?

• A. Float
• B. Thermocouple
• C. Pressure switch
• D. pH probe

Answer: (A)

Level measurement transmitters convert how high the liquid is into an electrical signal. A float-type transmitter does this by using a buoyant float that rides on the surface of the liquid; as the level rises or falls, the float moves up or down, and that motion is translated into a signal (often 4-20 mA) by a connected mechanism. This directly provides a level reading, which is why a float is the correct choice for a level measurement transmitter. The other devices measure different properties—thermocouples sense temperature, pressure switches respond to pressure, and pH probes measure acidity—so they’re not level transmitters.