Tensiometer vs. Stalagmometer Readings
A discussion started in 2000 but continuing through 2017(2000)
Q. I am having trouble getting accurate surface tension measurements on a chromic acid anodizing bath using a tensiometer. Calibration with a known weight goes fine, but doing surface tension tests on DI water turn out 5-10 dynes/cm low. Results from the anodizing bath also seem low 18-24 dynes/cm. The bath's operational parameters are 26-40 dynes/cm, and stalagmometer readings are consistently in the mid 30's. I am using sterile petri dishes for sample containers, and I am cleaning the tensiometer ring in Acetone [linked by editor to product info at Amazon] with a DI rinse and then flaming the ring with a lighter until red-hot as the tensiometer instructions stipulate. The chromic acid and DI water samples are cooled to room temperature (25 degrees C). I would normally assume that the stalagmometer is just reading high, but the DI water tensiometer readings are low also, so I think the problem is with the tensiometer.
I read somewhere that tensiometer and stalagmometer readings on the same sample differ by 10-20 dynes/cm (the stalagmometer reading the higher). Has anyone else run into this difference also? Are there any suggestions for normalizing the two readings? Any information would be appreciated.Chris Start
- Plymouth, Michigan, USA
A. The best info I've seen on the subject is "Report on Observed Differences in Dynes/Centimeter Readings of Various Chromium MACT Method 306B Surface Tension Measuring Devices" by J. Hensley and David York, presented at AESF Week in 1997.
Upshot is that there is a differences, the magnitude of the difference depends upon the surface tension, and the difference changes with solution.
- Tallahassee, Florida
If we have sample which have viscosity in range of 2 to 8 dyne/cm and it is suspension like sample than what method you suggest for measurement of surface tension? Please provide me a guidance.
pharmaceuticals. - Ahemdabad, Gujarat, India
Not sure of guidelines in your state, but in California the guidelines for each are different.
According to the CA EPA Air Resources Board reference, #93102.8-Chemical Fume Suppressants
"In the performance testing, the hexavalent chromium emission rate of 0.01 milligrams per ampere-hour was achieved under conditions in which the surface tension did not exceed 45 dynes/cm by a stalagmometer or 35 dynes/cm by a tensiometer."
There seems to be 10 dynes difference in the measurement reading. Personally I use a stalagmometer, it's quite simple and little maintenance.
Chrome Plating - Stockton, California, USA
A. I have developed an instrument 'www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16571362, SURVISMETER, It measures both the viscosity and surface tension together with single instrumental unit.Man Singh
chemsistry research lab. - New Delhi, India
March 9, 2008
A. Stalagmometer surface tension drop count method Tubes are available in 2.5mL, 3.5mL and 5.0mL sizes.
Stalagmometer for Nickel, Acid Copper, Acid Zinc, Acid Dips and Pickles (5 ml)
Stalagmometer for Chromium (2.5 ml)
Stalagmometer Kit (includes: stand, filler bulb, beaker and counter) for Nickel, Acid Copper, Acid Zinc, Acid Dips
Stalagmometer Kit (includes, same as above) for Chromium
Stalagmometer surface tension drop count method
Surface tension has long been recognized as an important physical characteristic of fluids and colloids that can affect biological processes. Scientists sought ways to measure this phenomenon, but reproducible results were difficult to obtain. Two approaches, developed to measure this subtle force, are displayed here.
The process of drop formation by liquids is, in part, controlled by the surface tension of the fluid. To determine surface tension, the stalagmometer used a drop weight method, in which the number and weight of drops were compared to those from a reference liquid. Seemingly simple, the stalagmometer nevertheless required considerable skill and absolute cleanliness for readings to be meaningful.
- Boca Raton, Florida, USA
March 17, 2008
A. (engineering) An instrument for measuring the size of drops suspended from a capillary tube, used in the drop-weight method. Also known as stactometer; stalogometer. Tubes are available in 2.5mL, 3.5mL and 5.0mL sizes.Tim Wong
- Boca Raton, Florida, USA
May 16, 2011
Surface tension and interfacial tension are the functions of the cohesive forces. For example mercury has surface tension 465 dyne/cm at 25 °C while the water has 72.18 dyne/cm. This difference is because the Hg has highest cohesive forces but the water 6.44 times lower than of the HG.
Thus the difference in surface tension is function of nature of the molecule.
On the other hands the viscosity is a function of frictional forces which are created by the solid surface of the capillary with respect to liquid molecules flowing along capillary walls.
- Gandhinagar, India
September 27, 2011
This is easy. Dynamic (flowing) drops will always be heavier than tensiometer readings. This is because as the stalagmometer drop is separating, a finite time for this, it is being filled with additional fluid making it heavier. This is the holy grail, and I will be publishing a way to compare the two methods.Chuck Cronan
- Milwaukee, Wisconsin, USA
May 1, 2017
The use of survismeter is safer and resource saving along with most accurate results.Man Singh [returning]
- Gandhinagar Gujarat, India
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