This can be a big problem, and a problem that is easily avoided because in reality, using the proper measuring devices and following the correct procedures are very simple and easy to conduct. One reason why people avoid determining viscosity is that they are intimidated by the process and the measuring devices required. 1 mistake made when determining viscosity is AVOIDING the process of determining the correct viscosity, using the proper measure device! Instead, they do a “guesstimate” which oftentimes leads to an incorrect understanding of the true viscosity of the fluid you want to pump. 1 Mistake Made When Determining Viscosity for Pumping The formula for measuring viscosity is Shear Stress / Shear Rate = Viscosity expressed in Centipoise (CPS). Water is often used as a baseline for comparison. Centipoise is a popular method for measuring viscosity and is considered a dynamic viscosity measurement unit. Understanding the accurate viscosity rate of the fluid you are pumping is one of the most important, if not the most important factors for pumping viscous fluids. An EDDY Pump specifically designed for slurry applications that involve high viscosity and high specific gravity materials can pump materials that have a greater specific gravity range than most common centrifugal pumps usually, centrifugal pumps are on the lower specific gravity range compared to an EDDY Pump. The opposite is also true in that if the material has a density greater than 1 and is tossed in water it will sink.Īs an example, water has a specific gravity (of 1 Sg, and a typical sand/water mix in dredging ranges from 1.3 Sg to 1.8 Sg. An interesting fact regarding specific gravity is that if a material has a density less than 1 Sg, and that material is submerged in water it will actually float on the surface of the water. When a fluid’s specific gravity is greater than 1 Sg the fluid is denser than water, if the specific gravity is less than 1 Sg the fluid is less dense than water. For measuring the specific gravity of gases the comparison is usually the density of air. Specific gravity, also referred to as relative density, is the measure of a fluid’s density compared to the density of water. The converse is also true in that fluids experience an increase in viscosity due to the temperature decreasing. Temperature’s Role in Pumping High Viscosity FluidsĪ key point to keep in mind when pumping high viscosity fluids is that when the highly viscous fluid is exposed to increased temperatures the viscosity has a tendency to decrease. Another important item that must be understood is that higher viscosity fluids cause greater pipe friction loss. The opposite is also true in that when the temperature of the fluid decreases the viscosity increases which causes the material to become thicker and require a greater amount of force to cause the material to flow. Some other particulars regarding viscosity are that viscosity usually decreases when the temperature of the fluid increases which causes the material to become thinner and flow with less force applied. Essentially, viscosity indicates a fluid’s ability to resist the forces that tend to produce a flow of that material. Viscosity is the measure of a fluid’s thickness, and in particular, its ability to resist deformation at a given rate.
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