THE RING SHEAR TESTER
ASTM Standard D6773-02

Capabilities

The Ring Shear Tester provides computer-controlled measurement of the flow properties of powders and other bulk solid materials, under conditions which duplicate handling situations. Such properties are useful for:

• Product development
• Product characterization
• Quality control
• Comparative measurements
• Troubleshooting

Why Are Flow Properties Important?

A material's flow properties determine how it will behave in bins, hoppers, feeders, and other handling equipment. Knowing these properties is essential in product development so that flow problems can be avoided.

Flow properties are important also for quality control. By checking the relative flow properties of a given bulk solid before it is placed into your system, you can reject or recycle unsatisfactory batches, thereby preventing costly handling problems downstream.

What Flow Properties Need to be Measured

The most important properties are cohesive strength, internal and wall friction, and compressibility. While each of these parameters is affected by your material's particle size distribution, particle shape, surface characteristics, and moisture content, there is no direct correlation which allows these variables to be used to calculate or infer your material's flow properties. Therefore, only those testers which directly measure cohesive strength, internal and wall friction, and compressibility should be considered.

Why Choose the Ring Shear Tester

First, this is a real shear tester. This is important, since shear testers are the only internationally recognized means to measure the flow properties of bulk solids.

Second, this tester is easy to use, requiring minimal operator training and skill. In addition, the time required to test a material and analyze the results is minimal.

Third, this tester is extremely versatile. Materials which are free-flowing, very poor flowing, or require large shear deformation can all be tested. The applied stress level can be varied over a wide range, consistent with how your material is being handled. The tester can even be used to measure the attrition properties of materials such as granules, flakes and pellets.

Which model is right for you?

The new "small" Ring Shear Tester, model RST-XS, utilizes a 30 ml cell volume. This compares to the 900 ml cell volume of the standard tester, model RST-01.pc. The small sample size makes the RST-XS especially appropriate for the pharmaceutical industry, where large sample quantities can be difficult and/or expensive to produce. The small size of the RST-XS also makes it a bench-top unit, compared to the RST-01.pc, which is a floor unit. A comparison of when to use each tester follows.

General Testing Procedures

The powder sample is contained in an annular trough. A vertical load is applied through an annular, roughened lid. To shear the sample, the shear cell rotates relative to the lid, and the torque necessary for shearing is measured. As with the internationally recognized Jenike shear test (ISO, ASTM, EFCE standards), the sample is presheared and then sheared to failure so a yield locus can be developed. Simplified tests are also possible.

Several modes of operation are available. Standard test procedures can be used, where test parameters such as the consolidation stress are entered once. For special applications a semi-automatic test mode is provided. Here, the operator observes the measured data on the screen and controls the test via the PC keyboard.

Primary Operational Components

• Automated load application. The vertical load, N, as shown in the cutaway view, acting on the bulk solid sample is adjusted via computer commands, which direct a motor to shift weights on a lever arm. No weights need to be handled by the operator.
• Digitally controlled motor drive for shear cell rotation. Cell rotation, w (see cutaway view), is also computer controlled, providing flexibility, particularly when conducting particle attrition tests.
• Twin load beam shear force measurement. The shear force, F1 and F2 (see cutaway view), is automatically measured and the output is viewed in real time via a computer.
• Counterweight system. Testing at very low pressures is accomplished with a counterweight system (force, FA, as shown in the cut-away view) to reduce the weight of the cover.
• Inductive displacement transducer measures sample height. Material density is calculated during shear testing and compressibility testing.
• Model RST-01.pc is shipped with one standard shear cell, one reduced volume shear cell, and one wall friction cell (friction surfaces are not included). Model RST-XS is shipped with one standard (30 ml) cell. Standard cells are fabricated from aluminum. Stainless steel cells are also available.
• Computer software for controlling the ring shear tester and for detailed test data analysis.

Warranty Summary

For a period of six months, we will repair or replace any defects in materials or workmanship free of charge.

Standard PC Requirements

The unit must be connected to a computer (not included). Special PC cards are not necessary.

• 400 MHz (Pentium) processor, minimum
• Microsoft Windows 95/98/NT4.0/2000/XP.
• Serial communication port (RS-232)

Dimensions (Approximate)

Model RST-01.pc: 51 in. H x 41 in. W x 16 in. D; weight: 265 lbs.

Model RST-XS: 22 in. H x 24 in. W x 19 in. D; weight: 90 lbs.

Equipment Availability

For additional information or pricing, contact us at (978) 649-3300, by fax at (978) 649-3399, or by e-mail to test-equip12@jenike.com.