Chemical & Process Technology: Control Valve Selection

Thursday, March 4, 2010

Control Valve Selection

Control valve has been widely used in Chemical & Process Plant for material feeding control and operating condition control, material feeding control. Today control valve technology is highly reliability and availability and long life span. It is a very mature technology. There are many handbooks and articles available online and FREE for read and download. In the past a control valve related documents listed in "Useful Documents Related to Control Valve". This time i would like to highlight a few that i think they are rather complete and you shall not miss them.

Handbook For Control Valve Sizing
Besides two most important handbooks for control valve available free in the net, Parcol is also offering Handbook for Control Valve Sizing which is brief but informative in nature.

Valve Selection Essentials

Valve failures, replacements, repairs, downtime and lost product can be greatly minimized by selecting the right valve, the first time. Great. So how do you assure you are selecting the right valve? There are basically 3 avenues:

1. Evaluate your system criteria relative to each valve type.
2. Utilize the expertise of a consultant or the factory Technical Sales Representative.
3. Utilize one of the new Valve Selection Software Programs provided by various valve manufacturers.

Read more in Valve Selection Essentials

Control Valves Selection

Almost any type of valve can be used for control by fitting an actuator and positioner, though care must be taken to ensure that there is no excessive backlash present and it will be recognised many will not exhibit a good characteristic for precise control. A simple comparison table is presented in this article for easy selection.

Valve Selection for Compressor Surge Control

Surge is an aerodynamic flow instability which can lead to the catastrophic failure of the compressor system. One way to cope with this compressor flow instability is active control. For a laboratory-scale gas turbine installation, an active surge control system is proposed which consists of a plenum pressure sensor and a bleed / recycle valve. This work focuses on the selection of a control valve. More specifically, the required bandwidth and capacity of the valve are specified.

Sizing and Selection of Control Valves

The control valve is the most important single element in any fluid handling system, because it regulates the flow of fluid to the process. To properly select a control valve, a general knowledge of the process and components is usually necessary. This reference section can help you select and size the control valve that most closely matches the process requirements.

Sizing and Selection of Butterfly Valves

Control Valves are the most important element of a fluid handling system and proper selection of these valves is crucial for efficient operation of the process. When sizing butterfly valves for control, it is imperative to have certain requirements of the system. Maximum flow requirement would be equivalent to the design flow and provided or converted to gallons per minute and Maximum pressure drop allowed where typically 3 to 5 pounds max. However, the pressure drop should never exceed one half (1/2) of the inlet pressure. Without these two factors, selection of a control valve would be simply a guess...

Selecting a Control Valve
Fluid velocity in a control valve is a key parameter that must be considered when sizing and selecting a control valve. High velocity can lead to erosion damage, trim wear, trim component failure, vibration and high noise levels. Therefore, it is vital to design for valve velocities within acceptable limits so that these problems are avoided. A maximum body inlet velocity of...

Compressor Anti-Surge Control Valves
Surge Control Valves must be capable to operate the compressor below the surge control line. The surge control line is always depicted to the right of the surge limit line in the compressor curves (maps). Most information required for the sizing of the surge control valves is available on the compressor map. As the compressor suction pressure may vary, various calculations need to be made...More recommendations found in this article.

Butterfly Control Valves
Butterfly valve with large Cv compare to globe type control valve is commonly used for low pressure drop and low pressure rating system. It allow large flow passing through and induce low pressure drop. This article will present some facts and characteristic about Butterfly control valve...

Valve Sizing Info
Valve size often is described by the nominal size of the end connections, but a more important measure is the flow that the valve can provide. And determining flow through a valve can be simple. This technical bulletin shows how flow can be estimated well enough to select a valve size—easily, and without complicated calculations. Included are the principles of flow calculations, some basic formulas, and the effects of specific gravity and temperature. Also given are six simple graphs for estimating the flow of water or air through valves and other components and examples of how to use them.