Granular material flowmeter

Semi-automated measurement of powder flow rates through apertures

  • Description

    GranuFlow is an improved laboratory silo compared to the ancient Hall Flow Meter (ASTM B213, ISO4490)
    and compared to the “Flow Through An Orifice” method described in the Pharmacopeia (USP1174).

    GranuFlow combines a Stainless-Steel cell of 500 ml capacity and a rotating plate with 7 different holes with diameters from 1 to 38 mm.

    Holes diameters are manually increased while the measurement takes place.

    A dedicated electronic balance measures automatically powder mass flowrate without user dependency.

    • Principle

      The mass flowrate is computed automatically from the slope of the mass temporal evolution measured with the balance.

      The aperture size is modified quickly and easily with an original rotating system.

      The measurement and the result analysis are assisted by software.

      The flowrate is measured for a set of aperture sizes to obtain a flow curve.

      Finally, the whole flow curve is fitted with the well-known Beverloo theoretical model to obtain a
      flowability index (Cb, related to the powder flowability) and the minimum aperture size to obtain a flow (Dmin).

      The whole measurement is performed easily, quickly and precisely.

      • Key Benefits

        The measurement of mass flow through the various holes doesn’t require any disassembling and cleaning of the instrument.

        The configuration of the GranuFlow can be adapted to meet a wide range of cell capacities.

        • Differentiators

          The only automatic funnel flowmeter on the market.

          Able to measure precisely the flowability of powders through a full range of holes at once.

          Fast (less than 5min for the full Beverloo curve calculation), accurate and highly reproducible results (2% of accuracy, without user dependency).

          Intuitive results interpretation. Robust and easy to maintain.

          Delivered with intuitive software which allows the comparison of results. All data are automatically

          collected and stored for post processing. Easy data transfer and automatic report generation.

          Accurate estimation of the minimum drain diameter of the tested material.

          So-called cup tests take around 30 min, and impossible to obtain with the Hall flowmeter.

          • Applications

            Powders flowability measurements in a silo-funnel geometry.

            Powders flowability classification for the galenic formulation.

            Fast and accurate test for production line, able to detect problematic samples before their introduction inside the silo.

            • Options

              Extra rotating plates for high and low cohesion powders.

              Standalone version including ultrasonic sensor and electronic display for heavy duty environments.

              Calibration kit.

              • Specifications

              Dimensions L x W x H (mm)400 x 400 x 600
              Weight (kg)6.3
              Maximum cell size (ml)500
              Minimal sample volume (ml)50
              Computer requirementsDual core with 2.0GHz, 4Go RAM, Windows XP to 10 with up to date Service Packs
              ConnexionUSB 2.0 port
  • Theoretical Background

The mass flow rate F through a circular orifice of diameter D is given by the product of the mean speed of the grains <vout>, the aperture area and the bulk density ρ. One has the general expression,Image showing the expression of the mass flow rate F formulaThe Beverloo’s Law is based on two hypothesis

The flow is blocked when the orifice diameter is below a threshold Dmin.

The grains experience a free fall before passing through the orifice, i.e. image showing the expression of the falling speed formula

This relation comes from the idea that the jamming mechanism is due to the formation of a semi-spherical arch before the orifice. If this arch has a typical size proportional to the aperture, we obtain β = 0.5 To be more general, the parameter β can be a free parameter.

Finally, the mass flow rate expression becomes

image showing the final flow mass rate expression formula with β free parameter

Learn more with our Application Notes



photography of a white powder falling in a beaker using the GranuFlow
graph of SS 316L Virgin and Recycled powders using the GranuFlow compared to the Hall Flowmetergraph of the analysis of lactose powders showing F (g/s) versus the aperture size (mm) using the GranuFlow

Information RequestMeasurement Offer