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The Problem – Precision Detector for Viscometer If you are making complex molecules, how do you know your process is on target? Many petrochemical products contain long polymer chains that can change character quickly with only small deviations in the manufacturing process. Modern pharmaceuticals now include complex proteins and other molecules that are difficult to characterize by conventional methods. How can you be sure your thousand tons of plastic sheeting or that new wonder drug is going to meet spec? One tool to determine the nature of complex molecules is a precision viscometer. Viscosity is the internal resistance of a fluid to flow. Complex molecules typically interact with each other in a fluid and this can cause telling changes in viscosity. A polymer molecule in one state may have little interaction with its neighbors, and so its characteristic viscosity is low. In another state, the same polymer may interact strongly, and the resulting viscosity will be much higher. Measuring viscosity is often a reliable way to determine the state of complex molecules in a manufacturing process. The precision visometer is an important analytical tool in both research and production.
The Solution A fluid bridge is used to create a viscometer that is highly sensitive to small changes in product viscosity. A dual metering pump is used to pump two fluids along equal lengths of precision tubing. One side of the pump pushes a fluid of known viscosity. The other side of the pump pushes the test fluid along an identical length of tubing at precisely the same rate as the reference fluid. The difference in backpressure due to flow is a measure of the difference in the viscosities of the two fluids. Because one fluid has a known viscosity, the pressure difference observed between the two lengths of tubing can be used to determine viscosity of the test fluid. The differential pressure transducer is plumbed between the two tubes so that the backpressure difference due to fluid flow is measured directly.
Validyne Products The Validyne P55 transducer, specially fitted with chromatographic tubing fittings, is the ideal detector in a viscometer fluid bridge. The P55 is sensitive to the low pressure differences generated in precision visometry. The low internal volume of the P55 allows the system to respond to small changes quickly and to be flushed between test runs. The P55 is available with Valco fittings for connection to the precision tubing used in the fluid bridge.
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| Phone: 818.886.2057 || Email: Sales@validyne.com |
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