What are 3 types of level measurement/transmitters?

• A. Ultrasonic, Differential Pressure, Laser
• B. Thermocouple, RTD, Thermistor
• C. Pressure, Temperature, Humidity
• D. Capacitive, Magnetic, Optical

Answer: (A)

In level measurement, you determine how full a vessel is by sensing the material or the pressure generated by the column. Ultrasonic level transmitters send a sound pulse, wait for the echo from the liquid surface, and compute level from the travel time; they’re non-contact and work well for many liquids and some solids, though factors like foam or turbulence can affect accuracy. Differential pressure level transmitters rely on the hydrostatic pressure of the liquid column above a sensor, using P = ρgh to derive level (with known density and gravity); they’re robust for liquids and can handle dirty or viscous fluids, but require a good density value and a sealed interface. Laser level transmitters emit a laser and determine level via time-of-flight or triangulation to the surface; they offer high accuracy and fast response, with solid performance in clear or reflective surfaces but can be challenged by dust or steam and cost. These three represent common, direct methods for measuring level: ultrasonic, differential pressure, and laser. Other options describe temperature sensors or sensor families not typically used as standard level transmitters, so they don’t fit the question as neatly.