Suitable for measurements for product characterization and quality control, comparative tests, silo design.
The computer-controlled Ring Shear Tester RST Mk II can be used for:
- Determination of the flowability, e.g. for quality control, process optimization, or comparative tests.
- Measurement of flow properties (compressive strength, internal friction, bulk density, compressibility, time consolidation, wall friction angle, etc.) e.g., for silo design for flow
- Support of attrition tests.
Advantages and highlights of the Ring Shear Tester RST Mk II:
- The computer-controlled, automatic ring shear tester RST Mk II is an easy-to-operate shear tester. Shear testers are the standard measurement devices in bulk solids science & technology.
- Simplified operation of the tester and evaluation of the test results by using specially suited new computer software RST-CONTROL v3.
- Variable stress level: The flow properties are measured at the same stress level which is relevant for the application of the results.
- Measurement of "caking" or time consolidation, respectively, which is important if bulk solids tend to consolidate if they are stored at rest for a certain time interval). For storage under load the shear cell with the specimen can be removed from the tester. This allows to store the specimen in a climate cabinet, or oven. Further, the tester is not blocked and can be used for other tests.
- Wall friction test (wall friction angle, wall yield locus). Wall material coupons can be prepared by the customer.
- Various shear cell geometries (adjustment with respect to stress level and sample volume).
- Appropriate device for measuring the flow properties of bulk solids which are hardly to test with other testers, e.g. very elastic products (plastics powder, saw meal) and very cohesive, moist or extremely fine-grained products (e.g. sludge, moist clay, carbon black).
- Electric input: 24 V DC, 2 A (delivered with external power supply for 110 V to 240 V, 50 Hz / 60 Hz).
- Measuring system for normal and shear force: load beams with strain gauges.
- Measuring system for the sample height: inductive displacement transducer.
- Internal amplifiers, A/D- and D/A-converters, communication with a PC via its serial communication port or USB port.
- Normal force: Standard: max. 45 kg (ca. 450 N), i.e., a normal stress of approx. 20 kPa in the standard shear cell type M, approx. 50 kPa in the smaller cell type S.
- Shear cell (dimensions of sample volume): Standard: inner diameter 100 mm, outer diameter 200 mm, height 40 mm (sample volume ca. 900 ml).
- Smaller shear cells: see here.
- Shear velocity: ca. 0.05 - 30 mm/min (at diameter 150 mm).
- Dimensions of the tester (ca.): width 1040 mm, height 1300 mm, front-to-back-size 410 mm.
- Weight: ca. 85 kg.
RST-CONTROL software for measurement and evaluation
The Ring Shear Tester RST Mk II is supplied with the renewed RST-CONTROL v3 measurement and evaluation software. The software is to be installed on a PC (Microsoft Windows® 7/8/10/11* operating system) that is connected to the ring shear tester via USB or RS-232. RST-CONTROL controls the ring shear tester and, if required, automatically measures flow properties (yield loci), wall friction, compressibility, time consolidation, and more. RST-CONTROL supports the preparation of the measurement with the help of step-by-step instructions, and it automatically evaluates the test results.
*) Microsoft Windows® 7, Windows® 8, Windows® 10, and Windows® 11 are registered trademarks of Microsoft Corp., USA
Options and Accessories (for RST Mk II and RST-01.pc)
Generally, our Ring Shear Testers are delivered with a shear cell and a software package, so that different types of tests can be performed with this equipment, e.g. flowability tests (yield locus tests), time consolidation tests (caking tests), compressibility tests and attrition tests. For special applications, e.g. for time consolidation tests conducted on several samples simultaneously, for wall friction tests, and for tests with small powder specimens, we offer accessories as listed below.
Shear Tester RST Mk II is generally delivered with one shear
cell type M. This shear cell is the "standard shear cell"
for this tester with a specimen volume of 900 ml. Thus, this
shear cell offers a wide range of application, especially if
not only fine materials, but also bulk solids with larger
particles (e.g. granulates) have to be tested. Since 2022, a
new design (shear cell M v2, picture below) has been
available that offers advantages in terms of cleaning and
Shear cell type S (200 ml sample volume) corresponds in principle to the shear cell type M, but its main dimensions (diameter, height) are only 60 % of the main dimensions of type M . Shear cell type S is advantageous if a lot of time consolidation tests have to be run, because compared to shear cell type M less sample material is required, and less weights to adjust the consolidation stress are needed.
For applications where only limited amounts of powder are available, the shear cells type MV10 and SV10 have been developed. These shear cells correspond to shear cells type M and type S, but with a reduced specimen height of 10 mm.
The XS shear cell has an even smaller volume. With its small cross-sectional area, it is intended primarily for achieving high stresses (see table). It is connected to the ring shear tester with an adapter (see picture below).
table below gives an overview.
|M||"Standard shear cell" with about 900 ml specimen
volume, cross-section about 220 cm²
Maximum particle size depends on the type of powder and is about 10 mm for broad particle size distributions and 5 mm for narrow particle size distributions.
|S||"Smaller volume": About 200 ml specimen
volume, cross-section about 85 cm²
Maximum particle size depends on the type of powder and is about 5 mm for broad particle size distributions and 2.5 mm for narrow particle size distributions.
|MV10|| "Small volume": About 220 ml specimen volume at
large cross-section of 220 cm²
Maximum particle size depends on the type of powder and is about 2 mm for broad particle size distributions and 1 mm for narrow particle size distributions.
|SV10||"Small volume": About 85 ml specimen volume,
cross-section about 85 cm²
Maximum particle size depends on the type of powder and is about 1.5 mm for broad particle size distributions and 0.75 mm for narrow particle size distributions.
|XS||"Very small volume / large stresses": About 48 ml
specimen volume, cross-section about 32 cm².
This shear cell is intended to apply large stresses
on the specimen (maximum about 165 kPa).
Maximum particle size depends on the type of powder and is about 1 mm for broad particle size distributions and 0.5 mm for narrow particle size distributions.
For time consolidation tests in combination with the time consolidation bench (see above) weights are required for the adjustment of the consolidation load.
2 kg, 1 kg, 0.5 kg, 0.2 kg, 0.1 kg, 0.05 kg.
Accuracy: min. +/- 1%
Dimensions: thickness 10 mm to 14 mm, other dimensions depend on weight.
Weights are available as set or separately.
Time consolidation benches
A time consolidation test examines how a bulk solid consolidates when it is stored at rest (e.g. in a silo or IBC). To measure this, the bulk solid specimen is first consolidated with the ring shear tester, then stored under constant load, and finally sheared to failure. All of this can be done automatically with the ring shear tester, without having to remove the shear cell with the bulk solid specimen from the tester. The disadvantage, however, is that the tester is blocked by this specimen. Therefore, the use of a time-consolidation bench for external storage is recommended.
When using a time consolidation bench, the specimen is consolidated with the ring shear tester, then removed from the tester and placed on a time consolidation bench. The consolidation stress is exerted on the specimen through weights. After the consolidation period is over (e.g., after some hours, a day or a week), the specimen is returned to the ring shear tester and sheared again to measure the strength of the consolidated powder. Thus, one obtains a quantitative result on the increase of strength during the consolidation time, which is known as "caking".
time consolidation bench without cover (type 1SM-O) serves
for the storage of one shear cell (type M, S or XS, maximum
load 15 kg). The consolidation load is transferred to the
powder specimen through a vertical loading system provided
with a plate on top on which an appropriate amount of
weights is placed.
The time consolidation bench type 1S-O serves for the storage of one shear cell type S ore XS (volume ca. 200 ml, maximum load 15 kg). The consolidation load is transferred to the powder specimen through a vertical loading system provided with a plate on top on which an appropriate amount of weights is placed. The design without cover allows a more intensive contact between the powder specimen and the ambient atmosphere. This is preferable if the behavior of the powder in dependence on the ambient conditions has to be studied, e.g. by storing the time consolidation bench with shear cell and powder specimen in a climate cabinet or an oven.
Wall friction cells
Wall friction cells are required for the measurement of the wall friction angle or coefficient of wall friction (friction between a bulk solid and a wall material).
For the test, an annular wall material specimen ("coupon") is placed in the shear cell with the bulk solid specimen on top, i.e., the bulk solid is located above the wall material like on a hopper wall or a chute, which is absolutely necessary in order to avoid underestimating the wall friction angle in the case of segregating bulk solids. Wall material coupons can be made by the customer according to dimensions given in the tester's manual.
The picture above shows the current version of the wall friction cell (shear cell type WM v2), which offers advantages in terms of cleaning and weight. For fine-grained bulk solids (powders), there is an optional rough lid (picture below, principle as for the RST-XS.s ring shear tester) instead of the normally used lid with vanes/pockets which is preferable for coarse-grained bulk solids.
|WM||"Standard" wall friction cell, specimen volume
about 240 ml, outer diameter of the wall material
coupon about 215 mm.
Optionally with rough lid for optimization for fine bulk solids
|WS||Wall friction cell with specimen volume of about 95 ml, outer diameter of the wall material coupon about ca. 134 mm|
Technical modifications, misprints and errors excepted.