How many dynes per centimeter can a tensiometer measure?

By Hank Levi on Mon, May 06, 2013 @ 11:57 AM

If your reading this post you probably already have an understanding of a few basic concepts.  For those who missed it here they are for review.

Basic Concepts

  • A dyne per centimeter is a unit of force
  • A dyne is defined as the force required to accelerate a mass of one gram at a rate of one centimeter per second squared
  • A dyne per centimeter is the unit traditionally used to measure surface tension and interfacial tension
  • Surface tension is a measurement taken on a liquid and Interfacial tension is a measurement taken between/among liquids.
  • Surface tension and Interfacial tension are both measured using an instrument called a tensiometer

I suppose it's worth mentioning why we decided to write this particular post about tensiometers and their surface tension and interfacial tension measuring limitations.   The simple explanation being that people have continued to ask us the question!  In fact, one time we had someone ask if we could recommend a tensiometer that could measure up to and above 500 dynes per centimeter! ...and we simply said "why?" and scratched our heads.

I guess you could say we finally received enough inquiries about this to force us into action and write about it.

Tensiometer readout design

If you have ever looked at a manual tensiometer guage like this one you will notice the dial only goes to 90 (90 dynes per centimeter).  

manual tensiometer

Compare this to some of the automatic tensiometers that use sensitive electronic balances and software and you will notice they have for the most part (various models) a range up to around 100 (100 dynes per centimeter).  See the red arrows below;

automatictensiometerimage

Why not make them with larger ranges?

Up to this point you have seen a couple of examples of the range capabilities for a manual and an automatic tensiometer. The truth of the matter is that the dial on the manual tensiometer could be re-etched to include additional numbers going up much higher than 90.  And the automatic tensiometers using the electronic balances could be configured and the software re-written to go as high as 1,000! 

So why haven't the engineers who make these tensiometers made the range on their tensiometers as big as they can?  Wouldn't that make the tensiometer that much more appealing?  A bigger range would mean you could measure more samples right? 

Well maybe...but not on this planet or in this universe. 

Liquids and fluidic metals?

You see, the answer is not really about the tensiometer.  In general, except for fluidic metals there are no known liquids that will indicate a surface or interfacial tension above 90/100 dynes per centimeter.  Surface tension of Mercury for example is generally reported around 480 dynes per centimeter but it does not wet to either the Wilhelmy Plate or Du Nouy Ring and cannot be measured by a traditional tensiometer.  Other fluidic metals need high temperatures and special atmoshperic conditions and are also unsuitable for traditional tensiometers.  With the exception of fluidic metals just mentioned solutions including metal ions but excluding surfactants (e.g. plating solutions) indicate comparatively high surface tension readings of 80 to 90 dynes per centimeter at most.  One of the highest surface tension liquids except Mercury is Sodium Chloride 6.0mol/20°C at 82.55 dynes per centimeter (mN/m).

In summary then, we can conclude that all of the liquids we will encounter while measuring surface tension or interfacial tension with a traditional tenstiometer will fall in the range not to exceed 100 dynes per centimeter.  Therefore restating the obvious you don't need a tensiometer that can measure surface tension above 100 dynes per centimeter.

Make sense?

 

 

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About Scientificgear

By Hank Levi on Fri, Aug 31, 2012 @ 10:20 AM

describe the image

Scientificgear LLC provides several targeted areas of service including:

  • Karl Fischer Moisture Titration
  • Titration
  • Surface Tension (Tensiometers and Du Nouy Rings)
  • Contact Angle Analyzers for surface analysis
  • Thermal instruments (WBGT, Conductivity, Heat Flow)
  • Liquid Density Instruments (Benchtop and handheld)
  • Refractometers, Brix Meters

We support companies and organizations in select industries by providing:

  • Technical Support
  • Sales of Instruments
  • In-house and field repair service on select instruments
  • Calibration Service
  • Training and Installation
  • Some in-house testing
  • Manufacture and repair of Du Nouy Rings

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Du Nouy Ring Repair Service

By Hank Levi on Fri, Apr 06, 2012 @ 03:46 PM

Hi, this is Hank Levi, and I wanted to take a minute to tell you about what we're doing to provide repair service and replacement of new Du Nouy Rings.  We have been supporting operators working with popular manual and automatic tensiometers for about 10 years.  It may have been a result of the day-in and day-out working with these tensiometers that led us to where we are today...but it all started about 3 1/2 years ago when we started repairing Du Nouy Rings as part of our service.  About a year later we began providing New replacement Du Nouy Rings also.

Since then we have found customers who have needed help with Du Nouy Rings from other tensiometer manufacturers as well.  Last year Fisher Scientific stopped selling and servicing their tensiometers and with it their ability to provide Du Nouy Ring service.  We also discovered that customers of other manufacturers including Kruss, KSV, Kyowa, CSC, SEO and a few others might have a need for our du Nouy Ring service support too.

Well, the good news is that we are in the Du Nouy Ring business.  We can repair or provide replacement rings for any brand of Du Nouy Ring on the market.  This includes Du Nouy Rings for the popular Fischer Scientific Tensiomat, CSC Scientific, Kruss, KSV, Kyowa, SEO and more.

Do you have a need to have a ring repaired?  Or maybe you just need a new one.  Or maybe both.  Well we can help.  Just submit your contact information so we have a way to reach you and tell us what type rings you have.   We'll have someone contact you to review the details and if needed arrange to have your damaged rings sent in for service.
If you know of another person or organization that could benefit from our service please don't hesitate to forward this information to them.

Du Nouy Ring Repair ServiceCreated on 04/06/12 at 16:50:49

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How Much Does a Tensiometer Cost?

By Hank Levi on Mon, Sep 26, 2011 @ 03:37 PM

Tensiometers

 

Tensiometers are instruments used for conducting surface analysis on liquid substances.  Typical applications Tensiometers perform include measuring surface tension, interfacial tension as well as liquid density and Lamella Length on some Tensiometer models.  Some models can also perform other tasks including powder wettability and dynamic contact angle of a solid substrate.  Depending on the types of information the operator is seeking to find one model may be more appropriate than the other.

 

To help prospective users evaluate and compare the different types of models available in the market we have prepared a reference document we call the:

 

"Tensiometer Selection Matrix"

 

This matrix is not necessarily brand specific as it was designed to help those seeking to compare capabilities and prices among popular manual Tensiometer models vs. popular Automatic or "digital" Tensiometer models.

 

We hope you find the Tensiometer Selection Matrix helpful in your search and evaluation of Tensiometers.

 Created on 09/22/11 at 12:43:16

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How Interfacial Tension Helps Evaluate Emulsifications

By Hank Levi on Fri, May 27, 2011 @ 03:44 PM

oil and water emulsification

Measuring interfacial tension is effective in understanding how two or more immiscible liquids are, or can be - emulsified.

Immiscible liquids by definition are liquids incapable of being mixed to form a homogeneous substance.  Oil and water are immiscible.  We can act upon these immiscible liquids by emulsifying them into a single homogeneous substance referred to as an  emulsion.  Emulsifying two liquids that ordinarily do not mix well -such as oil and water- causes tiny droplets from one liquid to be suspended in the other liquid - forming an emulsion.

We refer to a liquid as a phase.  Where one phase meets another phase (liquid to liquid - oil to water for example) a boundary forms between them and an imbalance of forces occur.  The amount of the imbalance can attribute to an energy at the point where the two phases meet.  We refer to this energy as surface free energy where a measure of energy/area or interfacial tension as force/length can be observed.  Increasing the interface area by dispersing one liquid phase into another by emulsification or the use of a surfactant for example will result in a lower interfacial tension.  The Interfacial Tension is measured in Dynes per Centimeter using an instrument known as a tensiometer.

Understanding these relationships exist and measuring them under different testing conditions is important to understanding how many liquid products interact. Knowing the interfacial tension becomes more important for researchers on how best to pursue future R&D as well as for production managers to maintain quality control for existing products used every day.  Some examples of industry where effectively measuring and monitoring emulsifications is important include:

  • Food Products
  • Beverages
  • Dairy Products
  • Cosmetics
  • Chemicals
  • Pharmaceuticals
Developing fluid separation and dispersion of oils in dressings and mayonnaise are very commonly studied for food R&D.  Developing new cosmetic formulations are also popular and important. 
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Surface Tension of drinking water, human consumption & health

By Hank Levi on Mon, Apr 25, 2011 @ 02:46 PM

BBA 071 1542220We all know that surface tension affects our daily lives thru everyday applications like the ink you use in a pen, detergents for washing clothes, soap to clean your hands, paint for the house, just to name a few.  But Surface tension is more involved in your life than you may think.

Tap water is usually around 72 to 73 dynes/cm.  This can vary by temperature and other variables but for the sake of this blog post we will assume 73 dynes/cm.  Now this is where it gets interesting.  At 73 dynes/cm water will hydrate you.  Or does it?  You see, It is known that on a cellular level your body has to convert fluids to 45 dynes/cm to allow the water to penetrate the human cells.  Once water penetrates the cells it can hydrate and remove toxins from the cells.   If water cannot effectively penetrate human cells an accumulation can build up and over time cause the cells to die.  Amazingly, I have seen places around the world where people claim to have special water.  They claim their water has a lower surface tension and less colloidal minerals.  You knew this was coming..Yes, these same people have demonstrated good health as they easily live to be 100 years old!  And yes, they attribute this to their water.

Not surprisingly, I see web sites now that sell supplements to lower the surface tension of  water to improve your health.

Fact or Fiction you ask?
I think I am going to order some of these supplements and check it myself with a digital tensiometer!  As they say the proof is in the pudding. Or in this case the surface tension!

Stay tuned.  I will update my findings and how I did.

Thank You,
Gus

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