In our business, we use the word “sieve” to describe a piece of equipment that separates different sized particles using a woven wire screen. To others, “sieve” can mean something very different.
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Topics: ASTM, Particle Size Analysis, Sieve Calibration, Sieve Certification, Sieves, Sieving Process
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.
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Topics: Bound Moisture, Free Moisture, Moisture Analysis, Water Activity, Moisture Testing, Karl Fischer, Karl Fischer Titration, Moisture
“How Many Ways are there to Measure Moisture?”
That is a recurrent question in early discussions about moisture measurement problems. Is frequently asked in connection with specific products and applications. This is a basic primer on the main techniques.
Most Used Methods to Measure Moisture Content
There are four core methods. They include the use of heat, chemicals, electrical properties and electrro magnetic phenomena.
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Topics: Moisture
Regularly I’m asked the question; “How accurate is this moisture balance?”
The questioner asks for the answer in terms of percent (%) moisture. When I answer “it depends”, I always get the unspoken response, “Why did I ask this stupid idiot?”
Absolute Measurement
When you ask about the accuracy of something like weight or temperature the answers are straight forward and relate to the instruments' precision. For example 25 grams or 50 degrees plus or minus (+/-) 0.1 gram or 1/2 degree.
Percent is Relative
When you ask the question of how accurate is my percentage reading, the answer becomes complicated. It’s complicated because percentage (%) is a relative term. For example, the answer for the result of a Loss on Drying (LOD) moisture test, is based on the size of the sample you use.
Using the example of a LOD moisture test we can understand the concept. The result of this type of test is calculated by subtracting the weight of the sample at the end of the test from the weight of the sample at the beginning of the test. This difference is divided by the initial weight of the sample. This procedure produces a % moisture result.
Sample Size
In the following analysis, the implication s of sample size and instrument precision will be illustrated. This will be based on a sample that has 23.5% moisture and an electronic LOD moisture balance that has a sensitivity of 0.001 grams and repeatability of ± .005 grams.
Sample Analysis
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Topics: Moisture Analysis, Moisture Testing, CSC Digital Moisture Balance, Loss-On-Drying, Moisture, moisture balance, instrument accuracy
It’s easy to pretend you know the operating terms surrounding contact angle measurement. But do you really? For industries such as coatings, printing, and oil recovery, contact angle testing is an essential component of the production and/or quality assurance process. Having a competent understanding of these terms will make it so much easier to choose the right instrument for your company - one you can be certain will do what you need it to do.
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Topics: Surface Tension, contact angle, contact angle meter, dynamic contact angle, Liquid Properties
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.
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Topics: Sieve Shakers, Particle Size Analysis, Sieve Testing, Quiet sieve shakers, micron particles, nanometer particles, laser diffraction, segmentation
Peltier temperature control is becoming more common in viscosity testing, but traditional water baths are still the norm for many companies. Should you switch Peltier-based temperature control for you critical samples?
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Topics: Measure Viscosity, Viscometers, Viscosity, viscometer, rotational viscometer, differences in rotational viscometers
What are Viscosity Flow Curves?
A flow curve – also known as a rheogram – is a graphical representation of how a flowing material (fluid) behaves when it is subjected to increasing or decreasing shear rates. The corresponding shear stress and viscosity are calculated from the instrument’s parameters. You can tell what type of fluid (Newtonian/Non-Newtonian, thixotropic, dilatant, etc.) the sample is by the shape of the flow curve.
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Topics: Measure Viscosity, Viscometers, Viscosity
The first recorded application of density measurement was for fraud detection. The density measurement concept then expanded to encompass determination of material composition and assessment of product quality.
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Topics: density, oscillating u-tube, liquid density, hydrometer
When tempted to think I know all there is about surface tension measurement, further information brings me back to earth. I’m conversant with the principal applications: surfactant analysis, plating, detecting contaminants, development of ink and the like. I have assisted customers to set up and calibrate duNouy Ring tensiometers for most applications -- all the while taking for granted that the Ring technique was the method of choice -- with only infrequent questions arising about Wilhelmy Plate tensiometers.
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Topics: Wilhelmy Plates, duNouy Rings, Tensiometer, Surface Tension, interfacial surface tension, Liquid Properties, surface tension instruments, surface tension analysis, Digital tensiometer, automatic Tensiometer
