Crushing Strength
Applying Versatile Crushing Strength Tester (Vinci Technologies, France), crushing strength can be measured both for single pellets and extrudates, and for a bed of pellets (bulk crushing strength). The methods are suitable for measuring the strength performance of catalysts, carriers and sorbents. At least 100 pieces of sample pellets are required for measurement according to ASTM D4179, ASTM D6175 or 1 liter of sample according to ASTM D7084.
Samples are dried at 400 °С for 3 hours for moisture removal before the test. The temperature and time of heat treatment can be changed in agreement with the customer.
The method of measuring the mechanical crushing strength is to determine the force that must be applied to a pellet (or a bed of pellets) for destruction.
Determination and rate setting of the mechanical strength for catalysts, carriers or sorbents is necessary both in commercial production (for product quality control) and to ensure consumer properties (integrity of catalysts, carriers or sorbents during loading, unloading and operation of commercial devices).
ASTM D4179 Method
ASTM D4179 test method covers determining the resistance of formed catalysts to compressive force and is applicable to tablets and spheres of catalysts, carriers or sorbents. 100 individual pellets are required for testing. Each pellet is compressed at a rate of increasing force in the range from 0.44 to 4.4 daN / s (dan – decanewton) until its destruction. At the moment of destruction, the force value is fixed, in units of daN. If the catalyst is not spherical, then indicate its orientation during testing (radial or axial). The strength of the molded samples is calculated as the average value of the fracture forces in decanewtons. A standard test report may include the following data: average crushing strength; statistics table; histogram of nominal diameter; a histogram of the granule breaking force; a graph of the compressive strength depending on the nominal diameter; a detailed table of results for each pellet.
ASTM D6175 Method
According to the ASTM D6175 method, radial crush strength is measured by the component of individual pellets with a length-to-diameter ratio ≥1:1. 100 individual granules are used for the study. Each pellet of the extruded catalyst is compressed at a rate of increasing force in the range from 0.44 to 2.2 daN / s before its destruction. At the moment of destruction of the granules, the force value is fixed, in units of daN. The strength of the extruded samples along the generatrix is calculated as the average value of the ratios of the fracture forces in decanewtons to the length of the granules in mm (daN/mm). A standard test report may include the following data: average crushing strength; statistics table; histogram of the nominal diameter of the granules; histogram of the fracture force of the pellet; histogram of the fracture force divided by the length of the pellet; graph of compressive strength depending on the nominal diameter of the pellet; graph of crushing strength depending on the length of the pellet; detailed results table for each pellet.
ASTM D7084 Method
According to the ASTM D7084 method, the mechanical resistance to crushing or volumetric strength (at applied pressure in the range of 0.1 – 2.5 MPa) of a fixed bed of a solid catalyst, carrier or adsorbent is measured under conditions as close as possible to the operating conditions in a fixed bed. The result describes the crushing strength of the catalyst/carrier/adsorbent in the bed as a pressure in megapascals (MPa) acting on the catalyst bed, at which the number of small particles passing through the sieve with a cell size of half the size of the pellet is 1% by weight.