Hosokawa Micron’s sophisticated, state-of-the-art Powder Characteristics Tester PT-X is one of the company’s greatest success stories, with more than 4,000 of the instruments sold since 1969. Featuring in around 3,000 patents and thousands of international scientific papers and research documents, the PT-X is greatly valued by scientists, engineers and manufacturers around the world, who trust the reliable laboratory equipment to help design and optimise high-performance powder-handling and process systems, ensure excellent quality control and develop new and exciting powder-based materials.
Hosokawa Micron’s original Powder Characteristics Tester (the PT-A) was a world first; a truly ground-breaking instrument developed in the late 1960s in direct collaboration with Ralph J Carr Jnr. The American scientist devised ten methods of determining the flowability and floodability of more than a thousand dry powder types, which formed the basis of his Carr Index, now one of the most internationally recognised industry standards in powder processing.
The instrument has constantly evolved since the first commercial version became available in 1969 and the improved, 9th generation PT-X model is the result of years of collaboration between Hosokawa Micron and customers who have purchased previous models. This invaluable feedback has ensured the PT-X is replete with the latest features and functionality – such as dedicated statistical analysis software to assess repeatability, reproducibility and sensitivity – that address the needs of myriad, ever-evolving powder processing industries worldwide, including highly demanding pharmaceutical companies, as well as battery material and food manufacturers.
The Hosokawa Micron Powder Characteristics Tester PT-X is the ‘go to’ analysis equipment for measuring the flowability, floodability and compressibility of dry powders, using a collection of static and interchangeable components to perform eleven specific tests – such as a camera, elevating platform, polycarbonate cover/door, sieve holder frame and sieve screen, vibratory sample feeder, stationary funnel holder and stationary glass or stainless-steel funnel, cup holder and a choice of 25cc, 50cc and 100cc stainless-steel cups, cup extension, spatula, capturing tray, platform, weighing balance etc.
Now in its nineth incarnation, the Powder Characteristics Tester PT-X is the latest generation model and has been completely updated to feature the latest software and hardware technology, with functionality developed in collaboration with many of our existing Powder Characteristics Tester customers, who we canvassed to determine the improved features that were needed for the latest PT-X model to meet the specific and developing requirements of their industries.
In addition, thanks to design improvements and more user-friendly, step-by-step instructions and software, the processing time has also reduced by approximately 25%, making it much quicker to collate more accurate sets of results (around 20 minutes to complete all of the analysis per sample) and requiring less operator participation.
Reproducibility levels have increased by improved alignment between the fixed and interchangeable components, while stable feeding is effortlessly achieved by the automated vertical vibration feature with feedback control.
We have also reconfigured the instrument to make it 34% more compact than the previous model, which makes it even neater and easier to comfortably position on a work bench or countertop in laboratory and R&D environments.
The high-performance Powder Characteristics Tester PT-X has multiple uses connected to measuring the behaviours of dry powder materials, including even potential problematic samples, such as dusty powders and very small amounts of product. The industry-standard equipment is extremely useful during the process of designing powder-handling and process systems, for a product’s quality control and also for new material development and is utilised by myriad science and engineering industries worldwide, along with academic establishments. It is hugely popular in the pharmaceutical and nutraceutical sectors, right through to the food, mineral, battery and pigment industries.
Eleven Powder Characteristics Identified by the PT-X
The original Powder Characteristics Tester (model PT-A) was developed in the 1960s by Hosokawa Micromeritics Laboratory in close collaboration with Ralph J Carr Jnr, the American physicist responsible for devising the Carr Index. The first model was available commercially in 1969 and was entirely manual, so relied almost entirely on the capabilities of the operator. Today, the automated nature of the latest instrument , the Powder Characteristics Tester PT-X, has greatly improved its performance by producing more repeatable, accurate results in quicker time and has been integral to the development of more than 3,000 product patents internationally.
The Hosokawa Micromeritics Laboratory – established in 1958 in Osaka, Japan – was created to capitalise on Hosokawa Micron’s growing technical development skills, accumulated by knowledge gained since 1914, when the Hosokawa Micron company was founded.
Buoyed by a passion for research and development in the field of powder processing and engineering excellence, Hosokawa Micron’s founders established their laboratory as a stepping stone to formalising their research and development knowledge and skills, putting them on an equal footing with manufacturers in America and Europe, who were at similar stages.
The Hosokawa Micromeritics Laboratory worked closely with the Japanese academic community, specialising in powdered material and really being at the forefront of technologies for powder processing, underpinned by solid scientific and engineering knowledge. It continues to do so today, in the guise of the Powder Technology Research Institute, creating symposiums, academic journals, specialised engineering magazines related to powder engineering and the international KONA Award, established in 1990. Of course, Hosokawa Micron Group’s institute is still at the forefront of powder processing technologies, heavily involved in developing new and exciting processes and technology for advanced highly functional powders and systems.
The Powder Characteristics Tester PT-X is a versatile instrument famed for measuring no fewer than eleven properties of dry powder samples, through which their flowability, floodability and compressibility can be determined.
Extremely important for powder processing, the PT-X is of particular value to the pharmaceutical industry, which frequently uses the equipment in the production of powder-based medicines, where powder compressibility and flowability are critical to achieving optimised, high-value pharmaceuticals.
The compact, bench-top instrument is equipped with precision, interchangeable accessories that allow various tests to be performed, and features user-friendly software with simple instructions, set up diagrams and in-depth analysis capability suitable for performing the tests easily and achieving accurate, repeatable results.
Flowability Tests
Flowability considers how dry powder behaves from a stationary to moving state. The particles of a good-quality, free-flowing powder move independently of each other and are steady and consistent.
Measurements can be converted into a corresponding index number, as determined by the internationally recognised Carr Index for Flowability. The degree of flowability measurement comprises seven index categories: Very Good, Fairly Good, Good, Normal, Not Good, Bad and Very Bad and suggests corresponding measures that may need to be undertaken to overcome potential flowability issues, such as aggressive agitation, vibration or special techniques and apparatus that may be required to optimise a process.
There are five tests available that determine a dry powder sample’s flowability:
A direct indication of potential flowabilities of a powder sample. An image is taken to determine the angle of a dry powder sample as it is heaped following a period of electronically controlled vibration, which is conducted by the equipment. The angle is recorded by the software and converted to the relevant Carr Index category.
The relative measurement of loose and packed bulk density. Powders found to have more than 20% compressibility may require solutions to prevent bridge formation in a feed hopper and/or storage bin.
Measures a dry powder sample’s relative angle of internal friction by inserting a spatula into a vibrated heap of dry powder parallel to the bottom and then lifting it up and out of the sample. Two measurements are taken using the in-built camera to record two images.
The natural mutual attraction of dry powder particles and an excellent indicator of powder flowability. Handling equipment and feed hoppers should be optimally designed based on the results of this test, particularly if the powder has high cohesion properties. Cohesion figures in the Carr Index are used to measure fine and cohesive powders. Cohesion of a mean bulk density sample can be measured at three levels: less than 0.4g/cc (finer than 150 micron), 0.4-0.9g/cc (finer than 75 micron) and greater than 0.9g/cc (finer than 45 micron). High bulk density results in finer particles, therefore the finer the particles, the greater the surface area and the potential for cohesion is increased. The screens are weighed and paired with the software, as is the measuring cup and sample (whose weight is recommended by the software using the Carr Index but can be overridden). The vibration (amplitude) conditions and time taken to perform the test are calculated. The material is charged into the PT-X and the test begins when the polycarbonate door cover has been closed. The screens are removed individually, placed on the weighing balance and measurements are taken, which calculate the amount of material remaining in each screen and results in a cohesion value as per the Carr Index.
Defined as the percentage ratio of particles in a sample at the value d60 = d10. Uniformity figures in the Carr Index are used to measure granules and granular powders. The test can be completed for samples outside of the parameters of performing a cohesion test. Particle size needs to be determined first and the two values (d10 and d60) inputted into the software. The uniformity percentage is then determined by the software.
Floodability Tests
Floodable powder is characterised as having an unstable, liquid-like flow. Flooding is caused by a mass of particles fluidising because of air or other stimuli. Typically, the flow would be both uncontrollable and (usually) undesirable.
Measurements can be converted into a corresponding index number, as determined by the internationally recognised Carr Index for Floodability. The degree of floodability comprises five index categories: Very High, Fairly High, Tends to Flush, May Flush and Won’t Flush and suggests corresponding measures that may need to be undertaken to overcome potential floodability issues, such as whether a rotary seal is essential, potentially required or not required to prevent uncontrollable flushing of the powder during processing.
There are three tests available that determine a dry powder sample’s floodability:
Determined when G forces tap the heap of powder and changes its shape. Two angle measurements are taken (before and after) to determine where the powder’s Angle of Fall features within the Carr Index
The Angle of Difference is determined by the PT-X calculated the difference between the Angle of Repose (flowability) and the Angle of Fall (floodability). The greater the value, the more of a flushing characteristic the sample will have.
Relates to the scattering/dusting and/or flushing of a sample of dry powder. If the dispersibility is determined to be greater than 50%, the sample is considered to have a highly uncontrollable flushing characteristic. First, the weighing balance needs to be paired with the PT-X software and then the watch glass needs to be weighed and placed in the dispersion holder on the side of the PT-X. Then, you pair the weighing balance with the sample holder in place, take a sample, add it into the sample holder and weigh the filled sample holder. Remove the sample and holder and charge it into the closed gate of the polycarbonate tube of the dispersion holder, open the gate and the sample drops down onto the watch glass, which has been place securely inside a stainless-steel pan. The test is complete, the pan is removed, the watch glass taken out and the glass is placed on the weighing balance to measure its weight and how much material has remained on the glass without splashing out of it, thus the percentage of dispersibility is calculated by the software, which can be translated to the Carr Index.
Compressibility Tests
Compressibility considers the percentage differential between a sample of aerated product and a sample of tapped product. The volume of material for both tests is defined by using the same sized cup (a choice of cup sizes is available). Results from the tests are applied to the Carr Index via the software to ascertain the compressibility value.
There are two tests available that determine a dry powder sample’s compressibility:
When measuring the Aerated Bulk Density of a dry powder sample using vibration and a feeding hopper, it is important to note that it is a ‘one pass only’ operation, whereby a previously weighed sample enters the cup until it overflows and no more material can be introduced to the sample in the cup thereafter. Vibration stops, the excess heaped material is removed using a special method to ensure the sample fills the cup to the brim and is not compressed in the process. The filled cup is carefully removed and placed on the weighing balance to determine the aerated weight in grams of material per millimetre or cc.
Complying with the FDA, USP, ASTM and Kawakita’s Equation for Compressibility, the Tapped Bulk Density measures a defined amount of previously weighed sample by performing 180 taps to compress and remove the air from the material. Unlike when measuring the Aerated Tap Density, additional product can be introduced into the cup being tapped, if required, to complete the test in one operation. When the tapping has been completed, the sample is levelled off in the cup and the tapped (packed) weight of material is measured so the percentage of bulk density, relative to the aerated value, can be determined.
The Powder Characteristics Tester PT-X is typically sold as an individual piece of equipment and is commonly found in academic, research and laboratory settings for the purposes of testing and ascertaining the behaviours of dry powders.
For commercial use, the instrument is an excellent addition to powder processing and manufacturing scenarios where a high-quality, consistent powder needs to be produced from one or more powder ingredients and as such, can be used in conjunction with most of the powder processing equipment that forms the basis of the Hosokawa portfolio, including products for size reduction, mixing, blending, agglomeration, compaction and drying, along with containment.
Hosokawa Micron Group is a world-leading expert in the processing of powders, particles, liquids and other materials, including materials that are (or can become) an explosion risk. Our industry-leading equipment and process systems across the entire portfolio combine high-quality construction materials, aesthetic, practical and ergonomic design and engineering, plus the latest technology and processing theory, with all equipment and process systems meeting and even exceeding current European and international safety standards.
Offering one of the most diverse portfolio ranges available for powder and particle processing, our efficient, robust equipment and process systems are chosen by SME to multi-national blue-chip companies across the globe, from industries including pharmaceuticals, chemicals, cosmetics, food and beverages, minerals, nuclear, plastics, rubber, powder coatings, toner engineering, batteries and recycling.
A highly professional in-house project management and engineering service, along with in-house technical services – such as contract manufacturing, particle design, process testing, process optimisation and material testing – offer you an entirely bespoke solution to match our adaptable high-performance products and the process systems that we can precisely engineer and tailor-make for you.
Our wealth of knowledge and expertise encompasses every stage of the processing of your raw material, from R&D, feasibility studies and testing, even as far as conveying, weighing, dosing, storing and delivering your processed bulk solid material in the most efficient, clean, hygienic and safe way.
As you would expect, the equipment portfolio is also underpinned by extensive lifecycle management services and friendly, efficient customer care to support you during the decades of service you can expect to enjoy from Hosokawa Micron Group equipment and process systems.
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