Granular material heap analyzer

Automated repose angle and cohesive index measurements

  • Description

    When a powder is poured onto a surface, a heap is formed.

    It is well known that both the repose angle and the heap shape strongly depend on grain properties.

    In particular, a cohesive powder forms an irregular heap while a non-cohesive powder forms a regular conical heap.

    Therefore, a precise measurement of the heap shape provides useful information about the physical properties of the powder sample.

    • Principle

      GranuHeap instrument is an automated heap shape measurement method based on image processing and analysis.

      A powder heap is created on a cylindrical support with an initialization tube.

      After filling the initialization tube by hand with a fixed volume of powder, the tube goes up at the constant speed.

      Thereby, the powder is flowing from the tube to form a heap on the cylindrical support.

      A controlled rotation of the support allows obtaining different heap projections corresponding to different heap orientations.

      A custom image recognition algorithm determines the position of the powder/air interface.

      The repose angle refers to the angle of the isosceles triangle with the same surface than the powder heap projected image.

      This isosceles triangle corresponds to the ideal cohesiveness heap shape.

      The repose angle is computed for each image, i.e. for each heap orientation.

      Afterwards, an averaged value is computed.

      In general, the lower the repose angle is, the better the powder flowability is.

      The deviation between the real heap interface and the isosceles triangular heap provides the static cohesive index, which is computed for each image, i.e. for each heap orientation.

      This static cohesive index is close to zero for a non-cohesive powder and increases when the cohesive forces inside the powder strengthen.

      table that demonstrates the correlation between how good the flow is and the Repose Angle (in degrees) and the Static Cohesive Index from very very poor to excellent

      • Key Benefits

        Measurement is simple, fast and intuitive.

        Delivered with intuitive software, both average and variance are easy to access and allows the comparison of results. Accessibility is password protected.

        All pictures and data are automatically collected and stored for post processing.

        Easy data transfer and automatic report generation.

        Closed system for safety requirements.

        Size compatible with hood or confined enclosure.

        Recorded standard operating procedures that increase measurements repeatability.

        • Differentiators

          Fully automatic including the powder heap shaping.

          High measurement reproducibility due to rotational method.

          Easy cleaning by design using a collecting container under the heap.

          Calibration kit.

          • Applications

            Easy and fast flowability classification between powders.

            Perfect tool for the galenic formulation, that helps to detect problematic samples before their introduction inside the process.

            • Options

              Extra cells for small samples and adapted support.

              Special Pharma and Precious metal pack for ultra-small samples (4ml).

              • Specifications

                Dimensions L x W x H (mm)560 x 360 x 570
                Weight (kg)18
                Sample volume (ml)From 4 to 80ml
                CameraUSB 2.0. Monochrome CMOS Camera
                Light sourceLED Screen background lightning
                Frame resolution400 x 600 pixels
                Computer requirementsDual core with 2.0GHz, 4Go RAM, Windows XP to 10 with up to date Service Packs
                ConnexionUSB 2.0 port
  • photographies showing the cohesion, flowability and repose angle of a powder in the GranuHeap

    Learn more with our Application Notes


    photography of the GranuHeap instrument which is an automated heap shape measurement method based on image processing and analysis
    photography showing a grey powder on the metal cylinder of the GranuHeap instrument
    photography showing a mass of white powder in front of a black background

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