Shear Cell Testing and Particle Characterization: The Foundation of Reliable Process Equipment Design
Introduction
Designing bulk solids handling equipment - whether it's a silo, heat exchanger, feeder, conveyor, or mixer - can be a challenging task. Unlike liquids, bulk solids exhibit complex behavior that varies dramatically with particle size, shape, moisture content, consolidation stress, and environmental conditions. The consequences of poor design are severe: arching, ratholing, segregation, uncontrolled discharge, and costly production downtime.
The key to avoiding these failures lies in accurate particle characterization. One of the most critical methods to characterize particles is shear cell testing. This blog post explores the different types of shear cell testing equipment available today, the leading providers of testing services, and why investing in proper material characterization is critical when designing process equipment.
Why Particle Characterization Matters
Before any piece of bulk solids equipment is designed, engineers must answer a fundamental question: How will this material actually behave under real process conditions?
Bulk solids are not uniform. A granule that handles well at room temperature may cake after storage in a hot, humid environment. Minerals from one section of a quarry may behave differently than the ‘same’ material from a different section of the quarry. Without quantitative data on flow properties, equipment design becomes guesswork—and guesswork often yields expensive results.
Accurate particle characterization provides the data needed to:
· Design hoppers and silos that guarantee mass flow rather than funnel flow
· Calculate minimum outlet dimensions to prevent arching and ratholing
· Select appropriate wall materials and surface finishes to control wall friction
· Predict time consolidation effects (how a material gains strength during storage)
· Troubleshoot existing flow problems with data-driven solutions
Spending time up front to better understand the behaviour of the material you’re working with can save an enormous amount of time and effort down the road.
Types of Shear Cell Testing Equipment
Shear cell testers are the standard for measuring the flow properties of powders and bulk solids. They operate on a common principle: a sample is consolidated under a known normal stress, then sheared to measure the stress required to initiate flow. The resulting data form the basis for quantitative equipment design.
1. The Jenike Shear Tester
The Jenike Shear Tester is the original and most widely recognized shear cell, developed by Andrew Jenike in the 1960s and codified in ASTM D6128. These are getting harder to find ‘in the wild’ but are still used by many labs and service providers. While these testers are a recognized industry standard, they are difficult and labour intensive to use relative to other testers. Full disclosure – the first time I tried to use one of these the results were impressively inaccurate (100% due to operator error).
2. The Schulze Ring Shear Tester
The Schulze Ring Shear Tester (RST) was developed by Dietmar Schulze in Germany, it addresses many of the limitations of the traditional Jenike cell by using a rotational rather than translational shear mechanism. The instrument is available as a highly automated instrument and is widely used within industry. Many high-volume testing labs rely on this equipment as the possibility of operator induced error is much lower.
3. The Brookfield Powder Flow Tester (PFT)
The Brookfield Powder Flow Tester is another rotational shear cell that operates on principles similar to the Schulze tester. It is widely used in quality control and research applications, particularly in the pharmaceutical and food industries. Similar to the RST the PFT is highly automated. The PFT is more limited than the RST and Jenike tester but is generally more affordable than other testers and can provide an economical option for in-house quality testing.
The Need for Accurate Testing Conditions
Regardless of which shear cell is used, the quality of the results depends critically on testing under representative conditions. This is a point that cannot be overstated.
Bulk solids are sensitive to:
· Moisture content - surface moisture can migrate into particles during shipping, changing flow properties
· Temperature - many materials behave differently when hot vs. cold
· Time at rest - consolidation during storage can dramatically increase cohesive strength
· Particle size distribution - even small changes in particle size can alter flowability
It is often preferable to perform on-site testing when materials are hazardous, toxic, or change properties over time. By the time a sample has been drawn from a process, packaged, shipped, and prepped for testing – many characteristics may have changed.
On-site testing with portable equipment helps to ensure fresh samples, accurate environmental conditions, and representative results - though it does come with the additional inconvenience of getting staff and equipment to site.
Leading Shear Cell Testing Service Providers
Jenike & Johanson
Jenike & Johanson is the pioneer of bulk solids flow testing and consulting. Founded by Andrew Jenike, the company developed the foundational shear testing methodology that remains the industry standard today.
Solids Handling Technologies, Inc.
Solids Handling Technologies, Inc. has been providing bulk solids testing and consulting services since 1997. Founded by Joseph Marinelli, a former consultant with Jenike & Johanson, the company brings decades of practical experience to every project .
Solids Solutions
Solids Solutions, based in the Netherlands, provides comprehensive bulk solids characterization and powder testing services, including ring shear testing.
Beyond Shear Testing: Complementary Characterization Techniques
While shear cell testing is essential for flow property measurement, comprehensive process equipment design requires additional characterization. Basics like particle size distribution (bonus marks for shape information), bulk density, moisture content, and angle of repose should be known for almost any design situation and there are even more characteristics required for specific processes.
Conclusion: Invest in Characterization, Avoid Costly Failures
The design of reliable bulk solids handling equipment is not guesswork—it is engineering based on measured material properties. Shear cell testing, whether performed on a classic Jenike tester, a modern Schulze ring shear cell, a Brookfield PFT, or other analytical instrument provides the quantitative data needed to design hoppers that don't arch, silos that don't rathole, and feeders that deliver consistent, controlled flow.
The cost of comprehensive shear cell testing and particle characterization is a fraction of the cost of a single production outage caused by poor equipment design.
Keywords: shear cell testing, powder flow testing, bulk solids characterization, Jenike shear tester, Schulze ring shear tester, Brookfield powder flow tester, particle characterization, hopper design, silo design, flow properties testing, bulk material testing services, cohesive strength, wall friction, flow function, time consolidation, powder rheology, process equipment design