12/27/2023 0 Comments Volumetric flowIn addition, all safety or toxicity information should be provided, together with detailed data on the fluid’s composition, presence of bubbles, solids (abrasive or soft, size of particles, fibers), tendency to coat, and light transmission qualities (opaque, translucent, or transparent?).Įxpected minimum and maximum pressure and temperature values should be given in addition to the normal operating values. The fluid and its pressure temperature, allowable pressure drop, density (or specific gravity), conductivity, viscosity (Newtonian or not?), and vapor pressure at maximum operating temperature are listed, together with an indication of how these properties might vary or interact. If remotely, should the transmission be analog, digital, or shared? And, if shared, what is the required (minimum) data-update frequency? Once these questions are answered, an evaluation of the properties and flow characteristics of the process fluid, and of the piping that will accommodate the flow meter, should take place (Table 1). The first step in the flow sensor selection process is to determine if the flowrate information should be continuous or totalized, and whether this information is needed locally or remotely. The development of specifications that state the application requirements should be a systematic, step-by-step process. Therefore, time should be invested in fully evaluating the nature of the process fluid and of the overall installation. The basis of good flow meter selection is a clear understanding of the requirements of the particular application. Those “inexpensive” purchases can be the costliest installations. One of the most common flow measurement mistakes is the reversal of this sequence: instead of selecting a sensor which will perform properly, an attempt is made to justify the use of a device because it is less expensive. It is also recommended that the cost of the installation be computed only after taking these steps. When choosing a flow meter, one should consider such intangible factors as familiarity of plant personnel, their experience with calibration and maintenance, spare parts availability, and meant time between failure history, etc., at the particular plant site. Since flow control is often essential, measuring the flow of liquids and gasses is a critical need for many industrial applications – and there are many different types of flow meters that can be utilized depending on the nature of the application. Other factors that affect liquid flow rate include the liquid’s viscosity and density, as well as the friction of the liquid in contact with the pipe.Ī flow meter (or a flow sensor) is type of flow instrument that is used to indicate the amount of liquid, gas, or vapor moving through a pipe or conduit by measuring linear, non-linear, mass, or volumetric flow rates. The basic relationship for determining the liquid’s flow rate in such cases is: Because the pipe’s cross-sectional area is known and remains constant, the average velocity is an indication of the flow rate. Velocity depends on the pressure differential that is forcing the liquid through a pipe or conduit. With most liquid flow measurement instruments, the flow rate is determined inferentially by measuring the liquid’s velocity or the change in kinetic energy. In other cases, inaccurate flow measurements – or failure to take measurements – can cause serious (or even disastrous) results. In some operations, the ability to conduct accurate flow measurements is so important that it can make the difference between making a profit or taking a loss. As see you can see two different formulas with different parameters, different assumptions and thus different limitations.Measuring the flow of liquids is a critical need in many industrial applications. Summing up: Both are formulas allow you to determine the approximate volumetric flow rate (with several limitations) from the pressure drop or the velocity profile. For your formula you basically assume a constant velocity across the entire cross-section but this approach may also be extended to a cross-section with an arbitrary velocity profile by averaging over the cross-section.
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