• Ultrasonic measurement principal
  • 26 ft or 36 ft measuring range depending on model
  • 4-20mA output or 4-20mA with HART output available
  • Hazardous location approval models available
  • Ingress protection: NEMA 4X, IP66


The Rosemount 3100 Series ultrasonic level transmitter is a liquid level transmitter based on ultrasonic technology that is suitable for many liquid applications. The Rosemount 3100 Series ultrasonic level transmitter is simple to set-up and operate. Once installed, maintenance is minimal. Non-contacting measurement with no moving parts eliminates the problems typically experienced with contacting instrumentation. The Rosemount 3100 Series ultrasonic level transmitter features 2 integral signal relays, corrosion resistant PVDF wetted material, simple push button programming, automatic temperature compensation, and a built-in LCD display.

The entry-level Rosemount 3101 ultrasonic level transmitter is designed for simple level or distance measurements over a range of 1 to 26 ft and a 4-20mA signal output.

The Rosemount 3102 ultrasonic level transmitter has two integral relays for level or distance measurements over a range of 1 to 36 ft. It also features volume and open channel flow calculations and a 4-20mA / HART output.

The Rosemount 3105 ultrasonic level transmitter is intrinsically safe for use in hazardous areas. HART digital communications are also provided. With a PVDF wetside, the Rosemount 3105 ultrasonic level transmitter can be used in most hazardous and corrosive applications. Apart from the integral temperature sensor, an optional external temperature sensor may be used with the Rosemount 3102 and 3105 ultrasonic level transmitters, which may be used to measure distance and level or calculate volume or flow in an open channel.

Ultrasonic Measurement Principle

Ultrasonic pulse signals are transmitted and reflected from the liquid surface. The transmitter 'listens' for reflected signals (echoes) and measures the time-delay between transmitting and receiving. The distance to the liquid surface is automatically calculated using the computed time-delay. An integral temperature sensor continuously measures the air temperature around the transmitter. It then computes the speed of sound in air, automatically compensating the distance for temperature effects. The 3102 and 3105 have a remote temperature sensor option. The distance measurement can be sent through the 4-20 mA or HART ® output.


Here's how some of our customers use this product...

Liquid Sucrose Tank Level Monitoring

The Background: Our customer is a health food company that needs a reliable way to monitor the level of sucrose storage tanks.

The Problem: Monitoring the level of those tanks is currently being done simply by estimating how much is leaving and entering the tanks. This method is, of course, highly unreliable which has led to frequent overflows.

The Solution: The head space in storage tank is vented to the atmosphere which makes it a good candidate for ultrasonic level monitoring. We suggested the Rosemount 3100 series installed in an 18" standoff tube on the top of the tank which is able to keep monitoring level even if the 20' tank becomes dangerously full considering the 12" deadband zone (sensor isn't able to measure distance within 12" of the front face of the sensor). The customer also purchased a Rosemount 3490 universal control unit which includes a dislay and allows for easy programming of alarms and lights to alert workers when the tank is sufficiently full.