How viscosity affects flow rates

A common question about peristaltic pumps is how viscosity affects flow. Simply put, if the viscosity rises the flow rate will go down. Nonetheless, when considering the use of peristaltic pumps for any application that requires pumping viscous fluids, it is necessary to understand various factors.

* Since the physical properties and shape of the selected pipe are related to the viscous fluid, it directly affects the flow capacity of the peristaltic pump. The tube bounces after it is compressed by the pressure roller. "Rebound" is the cause of suction. Generally, the greater the elongation of the elastomer, the stronger the ability to lift the viscous fluid. This is exactly the same as our Prothane II ™ tube. Geometrically, the larger the ratio of the wall to the inner diameter, the better the pumping out of the pipe as the pipe bounces back better during constant bending in the pump.

* As a general rule, the more the fluid leaves the pump, the lower the flow rate. There are several reasons for these losses; laminar flow loss, the nature of the fluid itself (whether it is a binder or a lubricant), and the quality of the fluid, to name a few. For applications where viscosity is a problem, we recommend that you pump overflow or at least place it as close to liquid as possible.

* As the pump speed rises, pipe bouncing time becomes shorter. In the case of a specific gravity of water or a fluid close to it, the increase in speed has little effect, but when pumping a heavier fluid there is not enough time in the pump head of the pipeline to decrease the flow rate per turn There are points. Full rebound

As a limiting example of these effects, the following figure shows the results of a flow test at three different speeds using a 750 series pump with two different inspiratory lengths. I sucked GOJOTM soap and water. The "Y" axis represents the number of pounds per revolution of the pump output. Water was used as a control reference. As is apparent from the graph, the water flow rate remains relatively constant at different rates and different capture lengths. The result of GOJOTM varies greatly as the flow rate of the pump decreases as the distance from the air source increases. As the length of the inlet of the pipe increases, the discharge per revolution decreases dramatically.

As shown in the figure, the constant for this experiment is radius, length and pressure. The variables are flow velocity and viscosity. The y-axis represents the flow rate and the x-axis represents the viscosity. As the viscosity increases, the flow rate decreases, resulting in a reduction in the linear or inverse curve relationship. Rheumatocytosis is a condition in which excess red blood cells are present. We have learned that increasing red blood cells earlier brings about an increase in blood viscosity. As blood flow decreases, rising blood viscosity directly affects blood flow. Therefore, the presence of erythrocytosis may adversely affect blood flow rate by lowering blood flow velocity.

A common question about peristaltic pumps is how viscosity affects flow. Simply put, if the viscosity rises the flow rate will go down. That said, there are a variety of factors that need to be understood when considering a peristaltic pump in applications where it is necessary to pump up a viscous fluid. * Since the physical properties and shape of the selected pipe are related to the viscous fluid, it directly affects the flow capacity of the peristaltic pump. The tube bounces after it is compressed by the pressure roller. "Rebound" is the cause of suction. Generally, the greater the elongation of the elastomer, the stronger the ability to lift the viscous fluid. This is exactly the same as our Prothane II ™ tube. Geometrically, the larger the ratio of the wall to the inner diameter, the better the pumping out of the pipe as the pipe bounces back better during constant bending in the pump.

The fluid flowing through the stationary surface undergoes a force countering the flow. This tendency to resist flow is known as the viscosity of the fluid. Fluids such as air have low viscosity, thicker fluids like water are more viscous, fluids such as honey and oil are more viscous. Viscosity represents the internal flow resistance of a fluid and can be regarded as a measure of fluid friction. The higher the viscosity of the liquid, the slower the flow rate. Viscosity can be measured by calculating the time required for a given amount of liquid to flow through the capillary under gravity. The more viscous liquid, the more time it takes. The viscosity can also be determined by measuring the rate at which the steel ball falls into the liquid. As the viscosity increases, the sphere descends more slowly. Viscosity is related to the relative mobility of individual molecules of a liquid relative to each other.