The Hounsfield tensometer is occasionally referred to as a universal testing machine. This is because with the correct attachments it can simulate other tests, such as compression tests. The attachment shown is mounted in the tensometer at each end. A small cylinder of material can be placed between the discs. ![]() Tensiometer in liquid. This type of tensiometer uses a platinum ring which is submersed in a liquid. As the ring is pulled out of the liquid, the force required is precisely measured in order to determine the surface tension of the liquid. The method is well-established as shown by a number of international standards on it such as ASTM D971. This method is widely used for interfacial tension measurement between two liquids but care should be taken to make sure to keep the platinum ring undeformed. Bubble pressure method to measure the dynamic surface tension of liquids 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 capillary radius) 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. Spartito battagliero pdf. See also [ ] • • • • • References [ ].
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