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barcode reading in asp.net CONTROL VALVES in Software
CONTROL VALVES Recognizing Code 128A In None Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications. ANSI/AIM Code 128 Printer In None Using Barcode generator for Software Control to generate, create Code 128C image in Software applications. X, fraction of maximum lift
Code 128 Code Set A Recognizer In None Using Barcode decoder for Software Control to read, scan read, scan image in Software applications. USS Code 128 Generation In C#.NET Using Barcode maker for VS .NET Control to generate, create Code 128B image in .NET framework applications. FIGURE 203 Inherent valve characteristics (pressure drop across valve is constant) I linear, II incmasing sensitivity (e.g. equal percentage valve), III decreasing sensitivity. Code128 Printer In VS .NET Using Barcode encoder for ASP.NET Control to generate, create Code 128 Code Set B image in ASP.NET applications. Painting Code128 In .NET Using Barcode generation for Visual Studio .NET Control to generate, create Code 128B image in .NET applications. In general, the flow through a control valve for a specific fluid at a given temperature can be expressed as: Encoding Code 128 Code Set B In VB.NET Using Barcode maker for Visual Studio .NET Control to generate, create Code128 image in .NET applications. Draw Barcode In None Using Barcode drawer for Software Control to generate, create bar code image in Software applications. 4 = fl&POtPl) Encode Code39 In None Using Barcode creator for Software Control to generate, create Code 39 Extended image in Software applications. Generate Barcode In None Using Barcode encoder for Software Control to generate, create bar code image in Software applications. (20.2) Generate GS1  12 In None Using Barcode generator for Software Control to generate, create UPCA Supplement 5 image in Software applications. GS1  13 Printer In None Using Barcode generation for Software Control to generate, create GS1  13 image in Software applications. where q = volumetric flow rate L = valve stem position (or lift) po = upstream pressure pt = downstream pressure The inherent valve characteristic is determined for fixed values of pa and p 1, for which case, Eq. (20.2) becomes Encoding Royal Mail Barcode In None Using Barcode printer for Software Control to generate, create RM4SCC image in Software applications. Creating ECC200 In .NET Using Barcode creator for Reporting Service Control to generate, create Data Matrix image in Reporting Service applications. 4 = f2W>
Creating EAN13 In VS .NET Using Barcode encoder for Reporting Service Control to generate, create EAN13 image in Reporting Service applications. Drawing UCC  12 In Visual C# Using Barcode encoder for .NET Control to generate, create UCC  12 image in .NET applications. (20.3) GTIN  12 Generator In Java Using Barcode printer for Java Control to generate, create UPC Code image in Java applications. Linear Creator In VB.NET Using Barcode generation for .NET framework Control to generate, create 1D image in VS .NET applications. For convenience let: and x = LIL,, m = dqmax where qmax is the maximum flow when the valve stem is at its maximum lift L,, (valve is fullopen) x is the fraction of maximum lift m is the fraction of maximum flow. Equation (20.3) may now be written m = 4hmax = f(L~Lnlax) or DataMatrix Printer In None Using Barcode maker for Font Control to generate, create DataMatrix image in Font applications. Draw EAN13 In Java Using Barcode encoder for Android Control to generate, create EAN / UCC  13 image in Android applications. (20.4) m = f(x) The types of valve characteristics can be defined in terms of the sensitivity of the valve, which is simply the fractional change in flow to the fractional change in stem position for fixed upstream and downstream pressures; mathematically, sensitivity may be written sensitivity = dmldx In terms of valve characteristics, valves can be divided into three types: decreasing sensitivity, linear, and increasing sensitivity. These types are shown in Fig. 20.3 where the fractional flow m is plotted against fractional lift x . For the decreasing sensitivity type, the sensitivity (or slope) decreases with m . For the PROCESS
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linear type, the sensitivity is constant and the characteristic curve is a straight line. For the increasing sensitivity type, the sensitivity increases with flow. Valve characteristic curves, such as the ones shown in Fig. 20.3, can be obtained experimentally for any valve by measuring the flow through the valve as a function of lift (or valvetop pressure) under conditions of constant upstream and downstream pressures. Ikro types of valves that are widely used are the linear valve and the logarithmic (or equal percentage) valve. The linear valve is one for which the sensitivity is constant and the relation between flow and lift is linear. The equal percentage valve is of the increasing sensitivity type. It is useful to derive mathematical expressions for these types of valves. For the linear valve, dmldx = a (20.5) where Q is a constant. Assuming that the valve is shut tight when the lift is at lowest position, we have that m = 0 at x = 0. For a singleseated valve that is not badly worn, the valve can be shut off for x = 0. Integrating Eq. (20.5) and introducing the limits m = 0 at x = 0 and m = 1 at x = 1 gives dm =
Integrating this equation and inserting limits gives a=1 Recall that the definitions of x and m require that m = 1 at x = 1. For CY = 1, Eq. (20.5) can now be integrated to give m = x (linear valve) (20.6) (20.7) For the equal percentage valve, the defining equation is dmldx = pm where p is constant. Integration of this equation gives (20.8) or where mo is the flow at x = 0. Equation (20.9) shows that a plot of m versus x on semilog paper gives a straight line. A convenient way to determine if a valve is of the equal percentage type is to plot the flow versus lift on semilog paper. The relation expressed by Eq. (20.9) is the basis for calling the valve characteristic logarithmic. The basis for calling the valve characteristic equal percentage can be seen by rearranging Eq. (20.7) in the form dmlm = /3dx or hmlm = @Ax

