Transversal (combinatorics)
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A Tensiometer as it applies to physics is an instrument used to measure the surface tension () of liquids or surfaces. Tensiometers are used in research and development laboratories to determine the surface tension of liquids like coatings, lacquers or adhesives. A further application field of tensiometers is the monitoring of industrial production processes like part's cleaning or electroplating.
Types
Goniometer/Tensiometer
Surface scientists sometimes use a Goniometer/Tensiometer to measure the surface tension and interfacial tension of a liquid using the pendant or sessile drop methods. It is a more difficult experimental measurement to accomplish and is not nearly as accurate as the Wilhelmy plate method described below. A drop is produced and the profile is then captured using a goniometer/tensiometer. The software then analyses the profile of the drop and makes a series of calculations. With pendant drops, in older, more obsolete software, the maximum diameter and the ratio between this parameter and the diameter at the distance of the maximum diameter from the drop apex is evaluated and formulas are used to derive on the basis of the Young-Laplace equation surface tension. In more current, more accurate software, the LaPlace equation itself is used to calculate surface tension for hundreds of pairs of data points along the profile of the drop. Sophisticated software routines automate this computationally intensive process.
Du Noüy-Padday method
Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church. This method uses a rod which is lowered into a test liquid. The rod is then pulled out of the liquid and the force required to pull the rod is precisely measured. This is a rather novel method which is accurate and repeatable. The Du Noüy-Padday Rod Pull Tensiometer will take measurements quickly and unlike the ring and plate methods, will work with liquids with a wide range of viscosities.
Du Noüy Ring Tensiometer
This type of tensiometer uses a platinum ring which is submersed in a liquid. As the ring is pulled out of the liquid, the tension required is precisely measured in order to determine the surface tension of the liquid. This method requires that the platinum ring be nearly perfect; even a small blemish or scratch can greatly alter the accuracy of the results. A correction for buoyancy must be made. This method is considered inaccurate compared to the plate method but is still widely used for interfacial tension measurement between two liquids.
Wilhelmy Plate Tensiometer
The Wilhelmy Plate tensiometer requires a plate to make contact with the liquid surface. It is widely considered the simplest and most accurate method for surface tension measurement.
Bubble pressure Tensiometer
Due to internal attractive forces of a liquid, air bubbles within the liquids are compressed. The resulting pressure (bubble pressure) rises at a decreasing bubble radius. The bubble pressure method makes use of this bubble pressure which is higher than in the surrounding environment (water). A gas stream is pumped into a capillary that is immersed in a fluid. The resulting bubble at the end of the capillary tip continually becomes bigger in surface; thereby, the bubble radius is decreasing.
The pressure rises to a maximum level. At this point the bubble has achieved its smallest radius (the capillaryradius) and begins to form a hemisphere. Beyond this point the bubble quickly increases in size and soon bursts, tearing away from the capillary, thereby allowing a new bubble to develop at the capillary tip. It is during this process that a characteristic pressure pattern develops (see picture), which is evaluated for determining the surface tension.
Because of the easy handling and the low cleaning effort of the capillary, bubble pressure tensiometers are a common alternative for monitoring the detergent concentration in cleaning or electroplating processes.