barcode reading in asp.net CONTROL VALVES in Software

Making ANSI/AIM Code 128 in Software CONTROL VALVES

CONTROL VALVES
Decoding Code 128C In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Make Code 128A In None
Using Barcode creator for Software Control to generate, create Code 128 image in Software applications.
In this form it can be seen that an equal fractional (or percentage) change in flow (Am/m) occurs for a specified increment of change in stem position (Ax), regardless of where the change in stem position occurs along the characteristic curve. The term /3 can be expressed in terms of ma by inserting m = 1 at x = 1 into Eq. (20.9). The result is p = ln(llma) Solving Eq. (20.9) for m gives m = moe Px
Reading Code 128 Code Set C In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
Code 128 Code Set A Maker In C#
Using Barcode maker for .NET framework Control to generate, create USS Code 128 image in .NET framework applications.
(equal
Paint Code 128A In .NET Framework
Using Barcode generator for ASP.NET Control to generate, create Code128 image in ASP.NET applications.
Creating Code 128B In .NET
Using Barcode creator for .NET framework Control to generate, create Code 128A image in .NET applications.
percentage
Make Code128 In Visual Basic .NET
Using Barcode generation for .NET Control to generate, create Code 128 Code Set B image in VS .NET applications.
EAN128 Creation In None
Using Barcode creator for Software Control to generate, create GS1-128 image in Software applications.
valve)
Data Matrix 2d Barcode Maker In None
Using Barcode creator for Software Control to generate, create Data Matrix ECC200 image in Software applications.
Code 128 Code Set C Creation In None
Using Barcode generation for Software Control to generate, create Code 128 Code Set B image in Software applications.
(20.10)
Printing Barcode In None
Using Barcode creation for Software Control to generate, create bar code image in Software applications.
Print UPC - 13 In None
Using Barcode creator for Software Control to generate, create EAN / UCC - 13 image in Software applications.
In integrating Eq. (20.7), the flow was assumed to be mo at x = 0. Mathematically this is necessary, because mo cannot be taken as zero at x = 0 because the term on the left side of Eq. (20.9) becomes infinite. In practice, there may be some leakage (hence mo # 0) when the stem is at its lowest position for a double-seated valve or for a valve in which the plug and seat have become worn. For some valves, especially large ones, the valve manufacturer intentionally allows some leakage at minimum lift (X = 0) to prevent binding and wearing of the plug and seat surfaces. For a valve that does shut tight and is also classified as an equal percentage valve, the equal percentage characteristic will not be followed when the valve is nearly shut. In practice, the control valve serves as a throttling valve and is not intended to be wide-open or completely closed during normal operation. In order to express the range over which an equal percentage valve will follow the equal percentage characteristic, the term rangeability is used. Rangeability is defined as the ratio of maximum flow to minimum controllable flow over which the valve characteristic is followed. Rangeability =
Make OneCode In None
Using Barcode drawer for Software Control to generate, create 4-State Customer Barcode image in Software applications.
Encode Data Matrix In Java
Using Barcode generation for Java Control to generate, create ECC200 image in Java applications.
mmax
Barcode Encoder In Java
Using Barcode creation for Java Control to generate, create bar code image in Java applications.
Decoding Code 128A In Visual Basic .NET
Using Barcode decoder for VS .NET Control to read, scan read, scan image in .NET applications.
min, controllable
Barcode Generation In Visual Studio .NET
Using Barcode drawer for .NET Control to generate, create bar code image in .NET framework applications.
GS1 128 Generator In Objective-C
Using Barcode generation for iPad Control to generate, create UCC.EAN - 128 image in iPad applications.
For example, if mo is 0.02, the rangeability is 50. It is not uncommon for a control valve to have a rangeability as high as 50. In practice, the ideal characteristics for linear and equal percentage valves are only approximated by commercially available valves. These discrepancies cause no difficulty because the inherent characteristics are changed considerably when the valve is installed in a line having resistance to flow, a situation that usually prevails in practice. In the next section, the effect of line loss on the effective valve characteristic will be discussed.
Bar Code Scanner In Java
Using Barcode Control SDK for BIRT reports Control to generate, create, read, scan barcode image in BIRT reports applications.
Barcode Drawer In VB.NET
Using Barcode drawer for Visual Studio .NET Control to generate, create barcode image in .NET applications.
Effective
Valve
Characteristic
When a valve is placed in a line that offers resistance to flow, the inherent characteristic of the valve will be altered. The relation between flow and stem position (or valve-top pressure) for a valve installed in a process line will be called the effective valve characteristic.
PROCESS
APPLICATIONS
water P O
FIGURE
20-4
Control valve with supply line.
Consider a control valve having an inherent linear characteristic to be attached to the end of a pipeline that delivers water to an open tank. A diagram of the system is shown in Fig. 20.4. If the pipe is of large diameter relative to the size of the control valve, the pressure drop in the line will be negligible and the full pressure drop pa - p1 will be across the valve as the lift varies between zero and one. In this case a plot of flow versus lift will give a linear relation as shown by Curve I of Fig. 20.5. This curve is for the flow of water at 5 C through a control valve for which C, = 4.0 and the overall pressure drop, po - ~1, is 100 psi. To show the effect of line loss, Curve II is constructed for the same conditions as Curve I, with the exception that 100 ft of 1.0 in. (inside diameter) pipe is used to supply the valve. Example 20.2 will give the detailed calculations used to obtain the results in Fig. 20.5. For 100 ft of pipe, the plot of flow versus lift gives Curve II, shown in Fig. 20.5, in which the curve falls away or droops from the linear relation that holds for no line loss. Since line loss is proportional to the square of the velocity, the line loss is very small when the valve is nearly closed, for which case the total pressure drop is across the valve. For this reason, Curves I and II in Fig. 20.5 are close together at low rates. A rule often followed in industrial application of control valves is that the pressure drop across the wide-open valve should be greater that 25 percent of the pressure drop across the closed valve. A valve not selected according to this rule will lose its effectiveness to control at high flow rates.
Copyright © OnBarcode.com . All rights reserved.