# Tips to Scale-up & Design

## Fluid Transport / Mixing

On the Required Power of Centrifugal Pumps (1712)
Centrifugal pumps are representative of the most common plant equipment and are used for transporting various fluids. The required power of the centrifugal pump is one of the important elements of pump selection, and calculation methods are shown in chemical engineering textbooks. Although these are simple formulas, they are often not well understood because they have different unit systems, or their assumptions are not clearly stated. Here, various equations for calculating the required power will be explained in terms of unit conversions. Furthermore, by considering the premises of the required power equations, we will also explain what kind of calculations are required depending on the liquid transport conditions. (Y. Kumagae)
Piping Line Pressure Balance (1711)
In a piping line which sends liquid from a column or tank to　another column or tank, a control valve is provided to adjust the flow rate. The control valve changes the valve opening position to adjust the flow rate, but in the piping line, the pressure drop of other devices such as orifice flowmeters and heat exchangers will also change according to the flow rate. Therefore, it is the pressure balance between the control valve and other devices that will determine the flow rate. In this paper, we will examine the relationship between the pressure drops, the flow rate and a control valve opening position considering a typical piping line model. (K. Yokoyama)
Control Valve Characteristics (1707)
A control valve adjusts a flow rate by obtaining a control signal and changing the valve opening position. The valve sizing is determined by considering the following three factors: the Cv value, the flow characteristic, and the rangeability. Typical flow characteristics are the linear characteristic and the equal percentage characteristic. These characteristics differ greatly with respect to the valve opening position. In this document, we will discuss control valves and their design, and examine the linear and equal percentage characteristics. (K. Yokoyama)

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