Base plate: The plate on which the pump and motor are mounted.
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Decanting: Gradually pumping from one container into another.
Dosing: A controlled method of pumping in order to discharge exact amount of fluids.
Flooded suction: If the pump is below the liquid source, and the suction is fed by gravity. This is a preferred method for centrifugal pumps.
Fluid: A state of material that continually deforms under an applied shear stress. Gas, liquid and plasma are examples.
Friction loss (pump): Friction between the pump and the process fluid results in loss of pressure. Different parts of the pump are more susceptible to this force than others.
Friction loss (pipe): The force produced as the process fluid flows through the pipes of a system. Caused by movement of the fluid internally as one fluid layer moves against another. Also caused by movement of the fluid against the pipe wall. Rougher pipes will lead to higher friction.
Open free flow: When the discharge pipe or hose is fully open at the end with no restrictions.
Self-priming pump: A pump that contains a reserve amount of process fluid that helps to create an initial vacuum and lift fluid from the source.
Specific Gravity (SG): The ratio of the density of a substance compared to the density of a reference (usually water at 4°C).
Suction line: The suction line of a pump system is piping which transports fluid material from its source to the pump itself.
Transferring: To move a substance, usually a liquid, from one place to another.
Variable speed motor: Can be used to control flow in the system by varying the impeller speed.
If you've ever talked to a pump technician or sales engineer about ordering the right pump for your application, you know they typically ask many questions. That's because they see the pump not only as a device for moving fluids but as the main component in a network of equipment and product attributes that all have to work together to maintain the flow throughout the processing system.
As you can imagine, using the wrong pump for your application can lead to processing slowdowns or shutdowns. Just as costly, the wrong pump can result in inconsistencies in product or the wrong product altogether. That's why pump representatives ask for information about your application.
Pump experts at CSI consider five key factors for pump size in sanitary applications in food, dairy, beverage, and pharmaceutical applications. In this article, we explain why the factors are so important.
While even more factors must be considered, these are the top five:
In processing systems, fluids are introduced into pumps under various conditions, with atmospheric pressure and fluid temperature, viscosity, and density all affecting the rate at which fluids make their way into the pump. At the point of entering the pump, several factors influence how the fluid continues on its way out of the pump.
One factor is pump design itself and its design-related operating parameters such as:
Another is the effect the pump design has on the fluid’s temperature, viscosity, and density. All of the factors combine to influence the pressure and flow rate of fluid as it enters and exits the pump.
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In processing systems, fluids are introduced into pumps under various conditions, with atmospheric pressure and fluid temperature, viscosity, and density all affecting the rate at which fluids make their way into the pump. At the point of entering the pump, several factors influence how the fluid continues on its way out of the pump.
One factor is pump design itself and its design-related operating parameters such as:
Another is the effect the pump design has on the fluid's temperature, viscosity, and density. All of the factors combine to influence the pressure and flow rate of fluid as it enters and exits the pump.
While fluids move from one location to another in a processing system, they change under varying pressure, flow, and temperature conditions. To meet the needs of a wide range of liquid products and their flow properties — for example, the range from water to oils to honey —manufacturers have designed a range of pump solutions.
Having a full understanding of the fluid and the process is critical to successfully choosing the right pump technology and right pump size. Alfa Laval and CSI always live by the mantra “Right the first time.”
~ Russell Jones, Commercial Sales Manager - Pumps, Alfa Laval
Differential pressure is the difference between pressure at the pump inlet and pressure at the pump outlet. The amount of pressure available on the inlet side of the pump is called Net Positive Suction Head available (NPSHa) and is determined by several factors in your system.
Pumps vary in how much pressure they require on the inlet side of the pump to work properly, which we refer to as Net Positive Suction Head required (NPSHr).
That's why your pump representative may have questions about the system components included before the pump, such as:
It's because they all have an effect on NPSHa as the fluid attempts to make its way into the pump.
Once the fluid is in the pump, the pump's mechanical action creates pressure to move fluids through the outlet side of the pump where the fluid now has to overcome pressure created by gravity and other components on that side of the system. The difference between inlet and outlet pressure is the pressure differential.
All pumps have minimum pressure requirements at their inlets in order to work properly. The technical phrase for the minimum requirement is Net Positive Suction Head required (NPSHr), and is often shown on the pump curve.
The Net Positive Suction Head available at the pump inlet must always be greater than the Net Positive Suction Head required (NPSHr) to avoid cavitation.
Because temperature-sensitive fluids change their flow properties with temperature changes, knowing processing temperatures helps with pump selection. Temperature is one variable that can affect product viscosity while it moves through pumps, pipes, heat exchangers, and other components. High viscosity means higher resistance to flow; while low means lower resistance to flow.
If you want to move water at 20 gallons per minute at room temperature, you can look at a pump curve to determine the pump size you need for any pressure situation within the pump's range. However, complications must be accounted for when the viscosity of your product is not the same as the viscosity of water or if it's processed at temperatures higher or lower than room temperature.
Some food sauces, for example, have low viscosity when heated but thicken to high viscosity when cooled. Similarly, heating honey makes it flow faster than when it cools down to room temperature. That's why it's crucial to know product type, viscosity, and processing temperatures.
Dynamic viscosity is a measure of a fluid's resistance to flow. We can imagine that water is less viscous — or resistant to flow — than corn syrup, so corn syrup has higher viscosity than water.
The good news is if you're not sure what your fluid viscosity is at its processing temperature, your processing expert can help. They can do rheology testing, which means you send in a product sample, they send that sample to a lab, and they provide you with the viscosity measurement from the lab.
Some liquids change viscosity when under stress or pressure, such as when they contact a rotating impeller inside a pump. Some liquids become less viscous (thinner) with increased force, while others become more viscous (thicker) with increased force. By comparison, other liquids, such as water, do not change their viscosity, no matter how much force is applied.
Positive displacement pumps deliver a constant flow of fluid at a given pump speed. When viscosity increases, however, resistance to flow increases, so to maintain system flow at higher viscosities, pumps require more horsepower.
Are you interested in learning more about Chemical Centrifugal Pump? Contact us today to secure an expert consultation!