Last week, as I was reflecting on a recent moisture content problem, I recalled our series “Loss-on Drying and Other Moisture Mysteries.” In that series I examined moisture chemistry in products. However, I did little to define moisture content.
CSC Scientific Blog
We continue to search for answers to the question "Is Sieve Calibration Really the Holy Grail?" As promised,we present Episode III of the Pequeño saga. You may remember him as a very small (150-micron) particle with many similar-sized family members who are determined to defeat sieve certification.
We get repeated queries about calibration of our DuNouy Ring Tensiometers. That makes me think that calibrating procedures to insure accurate surface tension measurment needs some clarification.
The other day, I woke up with a lingering quandary: Are the concepts of
Moisture Content and Water Activity the same thing?
As usual, I’ve decided to take on the task of clarifying the difference. I hope I pull it off.
From the perspective of someone who supplies instruments that measure moisture content, water activity has not been a primary consideration. However, I believe that comparison and contrast of these important concepts will be useful.
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.
Topics: Surface Tension Measurement, Surface Tension, duNouy Rings, Wilhelmy Plates, Tensiometer, Fisher Tensiomat, Tensiomat Trade-In, Liquid Properties, Digital tensiometer, Automatic Digital Tensiometer, automatic Tensiometer
Sometimes we encounter a product that is so simple and rugged that it would be tempting to deem it indestructible. Consider a stainless steel trough with a gate and etched numbers on the bottom. Seems simple and the stainless would make it tough, right? That is not the case, but it has survived nearly unchanged for more than 85 years.
- Is your concrete going to be strong enough?
Will you chocolates taste right?
Will your washing powder flow and dissolve as advertised?
Is there dangerous residue in your pill stock?
Will the “frack sand” keep the fractures open?
Is my salt of the correct grade?
If these are not correct, serious consequences could result (e.g. spoiled product, returned batches, rework or scrap).
“Why are my Moisture Test results inconsistent?”
That is an issue for many of you who test for moisture. We discussed the complexities and multiplicity of issues involved with moisture content determination in our “Loss-on Drying Moisture Analysis and other Moisture Mysteries” series.
In addition to intrinsic properties of test samples that may adversely affect moisture testing systems, automatic equipment parameter set-up, operator oversights and sample handling contribute to seemingly intractable moisture test result inaccuracies.
Within the catalog of questions we are asked is a category related to Calibrating duNouy Ring Tensiometers. The subject matter ranges from how, why and what is proven?
I guess the immediate and wise-assed answers are: