Bulk solids testing at a glance
With measured physical properties, it is possible to predict how a powder or bulk solid behaves in the silo, during discharge and in the process. EN 1991-4 expressly gives measured values precedence over estimated or tabulated values.
Here you will find all measurements with their parameters, the sample quantity required and the common procedure – from sample receipt to the test report.
Measurements, parameters and sample quantities
We measure yield locus, wall friction and compression density on standardised shear testers to ASTM D6682, the bulk density to EN ISO 60 or USP 616 III, the angle of repose to DIN ISO 4324 or ASTM D6393 and the sieve analysis to DIN 66165.
| Measurement | Parameters | Sample quantity | Use |
|---|---|---|---|
| Yield locus | φi, φe, τc, σc, σ1, σ2, ffc, K, flow density | 0.5 l for ffc, 1–2 l for the flow function | silo loads, outlet, rathole, flowability |
| Wall friction | φs, φd, μ, adhesion | 200–300 ml per wall material | silo loads, mass flow, wall material |
| Bulk and compression density | ρb0, ρb(σ), Hausner ratio, Carr index | about 200 ml per sample preparation | bulk unit weight γ, filling volume |
| Time consolidation | time consolidation factor, time yield loci, σc,t(σ1) | by arrangement | outlet and rathole after standstill |
| Angle of repose | φAR | by arrangement | squat and intermediate-slenderness silos, comparison |
| Moisture content | %M, %S, moisture on a dry basis | 100–200 g | classifying samples, effect of moisture |
| Sieve analysis | particle size distribution 63 µm to 2 mm, fines < 63 µm | by arrangement | segregation, comparing batches |
From enquiry to test report
- Enquiry You describe the bulk solid and the question; we choose the measurements and prepare a quote.
- Sample You send in the sample – if required with a wall sample or target moisture.
- Measurement Each measurement is carried out at least in duplicate.
- Results Test report and online evaluation in the customer portal, usually about two weeks after sample receipt.
Lead time
Results are usually available about two weeks after sample receipt – depending on laboratory capacity and the number of samples. Time consolidation tests can extend the standard lead time accordingly.
Test report and customer portal
The test report contains all measured values and parameters. In the customer portal, different measurements and samples can be set side by side and compared; after the measurements for silo design have been completed, the calculation tool to EN 1991-4 is also available there.
What the measurements are used for
Silo design and silo problems
For technological silo design to EN 1991-4, the measurements provide silo loads, outlet, rathole and hopper inclination. If problems occur in an existing plant, they lead from the symptom to the cause.
Comparison and quality control
For product changes, new suppliers or changing batches, the comparison of flowability shows whether a bulk solid can still be processed in the existing plant. Which parameters answer which question is shown in the fundamentals of bulk solids mechanics.
Frequently asked questions about bulk solids testing
- Which measurements are needed for silo design?
- Yield loci at a minimum of three different consolidation stresses, the wall friction on your wall material and the bulk and compression density. For squat and intermediate-slenderness silos (hc/dc < 2) we also determine the angle of repose.
- How much sample material is needed in total?
- About 0.5 litres is sufficient for a flowability measurement alone; for the measurements for silo design about 1 to 2 litres per sample are needed. The quantities for the individual measurements are given in the overview; we state the total quantity with the quote.
- How often is each measurement repeated?
- Each measurement is carried out at least in duplicate. If the measurements extend over several days or the values deviate unusually strongly from each other, we repeat them.
- How long does the measurement take?
- Results are usually available about two weeks after sample receipt – depending on laboratory capacity and the number of samples. Time consolidation tests can extend the standard lead time accordingly.
Have your bulk solid measured
Describe your bulk solid and your question – we choose the right measurements and prepare a non-binding quote for you.
- Measurements at least in duplicate
- Results usually about two weeks after sample receipt
- Test report and online evaluation in the customer portal