APG Level Probes/float level transmitters
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Level Probe Guide: Where Float Level Transmitters Stand Out

Posted on by Sami Wiser

Float level transmitters are a proven, reliable way to measure liquid level in tanks, silos, and process vessels. These sensors use a simple yet highly effective design: the long sensing stem (the level probe), a series of switches inside the stem, and a magnetic float that rises and falls with the liquid. As the float moves, the internal magnets trigger the switches as the liquid level rises or falls.

At Automation Products Group, Inc. (APG), we design and manufacture float level transmitters that perform in some of the toughest environments. Below is a clear guide to the technology, applications, and benefits, along with insights into why your operation might choose a float-based sensing solution.

Types of Float Level Transmitters

APG manufactures two primary float level technologies, each suited for different performance needs and environments: our RP line of resistive level transmitters, and our MPX and MPI lines of magnetostrictive level transmitters.

  1. Resistive (RP Series) Float Level Transmitters

Resistive level transmitters use a sensing stem packed with closely spaced switches and sensors. A permanent magnet inside a float moves along the stem and activates the reed switches to produce a continuous, highly repeatable level signal.

Best for:

  • General-purpose liquid level measurements
  • Cost-sensitive applications

  1. Magnetostrictive (MPX & MPI Series Float Level Transmitters)

Magnetostrictive level transmitters take accuracy and reliability to the next level. Instead of switches, the stem contains a wire waveguide. When an electrical pulse in sent down the waveguide, it interacts with the magnetic field inside the float. This interaction generates a strain pulse that travels back to the sensor. By measuring the time difference between the two pulses reveals the float’s exact position. This type of transmitter can also house multiple floats to measure more than one liquid, such as oil/water interface.

Best for:

  • High-Accuracy Applications
  • Multi-Liquid Interface Detection
  • Critical Process Monitoring

Common Applications for Float Level Transmitters

Float level sensors excel in industries where accuracy, durability, and reliability are essential. APG transmitters are commonly used in:

Benefits of Using Float Level Transmitters

There are several benefits to using float level transmitters over other liquid level sensing technologies.

  1. Reliable in Turbulent or Foamy Conditions

Float transmitters are not affected by foam, vapor, or surface turbulence.

  1. Stable in Extreme Temperatures and Pressures

They maintain accuracy in environments where pressure or temperature can create problems for pressure sensors.

  1. Exceptional Compatibility with Difficult Liquids

Float level transmitter are well-suited for:

  • Flammable Liquids
  • Corrosive Chemicals
  • Sour Crude
  • Sea Water
  • Raw Sewage

  1. Built-In Temperature Measurements

Many APG models can measure both level and temperature, reducing the need for separate instruments.

  1. Customizable for Your Application

APG offers customizable solutions, such as:

  • Stem length
  • Stem material
  • Float material and size
  • Multi-float configuration
  • Extended-level options

  1. Certified for Hazardous and Tough Environments

Several of our float level transmitters have certifications such as:

  • Hazardous Locations. Read more here.
  • CSA
  • ATEX/IECEx
  • Explosion Proof
  • Intrinsically Safe

This ensures safe, compliant installation in demanding industrial settings.

  1. Simple Installation & Low Maintenance

With minimal moving parts and a straightforward design, float transmitters offer:

  • Long service life
  • Low maintenance requirements
  • Easy installation: simply insert the level probe into the tank and wire it in

  1. Continuous, Accurate Level Monitoring

Float transmitters provide dependable, real-time level data for inventory management, automation, and process control.

If you’re looking for a dependable, long-lasting level measurement solution, a float level transmitter from APG may be the perfect fit. Reach out to our Sales team today, we’re here to help you select the right model for your application.

WRITTEN BY
Sami T.

Sami Thompson is APG’s Marketing Technical Writer and has been with the company since 2022. With a master’s degree in English from Utah State University and a 40-page thesis publication under her belt, Sami has a demonstrated strong writing background. In her free time, Sami enjoys reading and birdwatching.