Challenges of Bulk Solid Level Measurement


Angle of repose on a gravel pile

Measuring the level of bulk solids in bins, tanks, silos, and other types of vessels is difficult. Bulk solids present many challenges including the shape of the material surface, material characteristics, internal vessel structure, dust inside the vessel (especially during filling), and others.

Let’s take a look at why these pose a challenge to solid level measurement:

  • Shape of the material surface
    The surface slope of solids may be flat and smooth but more often they have a sloped and irregular cone shape surface known as the angle of repose. This shape of the surface can be affected by many variables such as the location of filling or multiple fill points for example. Calculating the level of the material becomes difficult with the angle of repose.
  • Material characteristics
    Particle size ranges from very fine powders like flour to very coarse materials like coal. The coarser the material, the more likely it is to clump, or leave space and pile up. Larger solid materials present an added challenge of multiple angles on the surface of the material.
  • Internal vessel structure
    It can be difficult to know the exact dimensions of the silo or tank the material is stored in. The vessel may also have ridges and other rough surfaces which could affect the ability of some technology to get an accurate level reading or calculate the correct volume or mass of the material.
  • Dust
    Many materials produce large amounts of dust during filling and discharging of the material which could cause interference with a level reading.

Ultimately, no single technology applies to all solid level measurement applications. There are many variables to consider when choosing a level measurement technology. Be prepared to answer these questions when considering the level measurement device for your next application.

  • Vessel height, diameter, shape
  • Material properties
  • Bulk density
  • Dielectric properties (radar or guided wave radar)
  • Build up potential, or stickiness
  • Accuracy required
  • Mounting location/size options for the sensor
  • Continuous or point level measurement

There are many different technologies available today and it’s important to consider these factors when deciding which technology is right for your application. We discussed some tank level technologies in an earlier post, “Tank Level Measurement Technologies”. Take a look at the matrix we put together to give you a quick view of some of the tank level technologies available.

In addition to these there are also point level sensors which are favorites due to their simplicity of setup and low costs. Vibrating level sensors and paddle wheel sensors are simple to install and operate and will give you an accurate point level measurement designed specifically for solid materials.

If you have questions about what technology would work best for your application, give one of our application engineers a call or send them an email. Bulk solid level measurement does present its own challenges but with the technology available today you can find the level measurement solution you need.

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