In past ramblings on particle size analysis we have touched on shakers, ASTM standards, sieve checking, separating small particles, inhibitors like static charges and how to get sieve tests done. A couple of things that we rarely addressed.Read More
CSC Scientific Blog
Do You Re-Certify? Compare with a Master Stack? Check with Calibration Samples?
What Does Recertification Give?
The ASTM E-11 committee has done a great job of establishing three levels of testing. These levels show the probability of a sieve’s mesh to be within the permissible variations. These variations relate to the size of openings in wire-cloth used for test sieves.Read More
Topics: Sieve Shakers, Mid-Point Sieves, ASTM, Particle Size Analysis, Sieve Calibration, Sieve Certification, Sieve Testing, Sieving Process, Quiet sieve shakers, RoTap, sieving, test sieve equipment, sieve mesh
Quiet Sieve Shakers
Recently in a quiet, reflective moment, I recalled my first work with sieve shakers. Horizontal motion with tapping was the basic shaker design. The Ro-Tap® was King, and there were few alternatives. Different shakers for special applications, such as the Mary Jane and one that was hung from the ceiling, were the exception.Read More
If you take Sieve Shakers for granted, you may be surprised to know that the selection of the right shaker can have a profound effect on your sieving results.Read More
Sieve testing, as I have stated many times, is the Cinderella of particle size analysis because it delivers more value than expected from something that’s so easy to use and relatively inexpensive. However, the problem with standard sieving techniques using wire mesh sieves is that they begin to exhibit accuracy problems in the lower micron sizes.
Visitors to our web pages often arrive with the question, “What is the Function of a Sieve Shaker?”
The simple answer is “to expose the particles in a sample to all the openings in each sieve in a stack”. A sieve stack is the result of fitting each sieve to be used in a given particle size analysis into the one above. The sieve with the largest mesh holes is at the top with each subsequent sieve of a tighter mesh size than the one above it.
Is Sieve Calibration Really the Holy Grail? Part II: Inside a Sieve Test
As I start on this second installment of The Adventures of Pequeño: The 150 Micron Particle, I wonder why I get myself into these serial onslaughts. However, a promise is a promise, so I shall press on.
You will recall from Part I: Sieve Certification, our little friend Pequeño, a particle on a determined quest to make it through sieves -- particularly those through which he should be too large to pass. In this scenario, Pequeño along with some of his family and friends -- all small particles about 150 microns in size -- are on their way to a sieve test.
In April, we published an article in "Powder-Bulk Solids" comparing certification process veracity with a sieve calibration process using calibrated glass microspheres (or beads). The certification process merely indicates that a sieve mesh conforms to a standard that has a wide tolerance regarding mesh openings. It is performed on a small number of openings. On the other hand, calibration using the calibrated beads results in a number representing the mean opening -- a result generated by actually performing a test encompassing at least 80% of the mesh openings.
The primary purpose of a sieve shaker is to provide motion to a sample in a test sieve.
An effective sieve shaker creates a motion that presents all the particles to all of the sieve openings and assists particles in passing through. This requires both rotary and vertical motion.
This process seems simple enough, but let's not be taken in.
The relative value of a sieve certification process vs a sieve calibration has perplexed me for a long time.