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| ALPHA-I - The User-Friendly Valve Sizing Program | |
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DeZURIK's new Windows-based Alpha-I (version 6.2) software performs valve sizing calculations and graphs installed characteristics for DeZURIK control valves based on your process conditions. The single, user-friendly input screen allows users to quickly select the most suitable valve for the process conditions input. The program was developed by DeZURIK to provide accurate valve sizing data based on ISA/Industry formulas. Alpha-I was designed with the operator interface in mind and every effort was made to facilitate users. Selection for fluids, units, pipe and valve data are window driven. Process information for up to eight conditions can be entered on one screen. All process conditions are calculated simultaneously. Warning messages are displayed to indicate when a potentially undesirable situation occurs. Enhancements included in version 6.2:
System Requirements [back to top]
Frequently Asked Questions (FAQs) [back to top]
What is Fp, why is it required and how is it used in Alpha-I? Fp is the Piping Geometry Factor, defined by ISA S75.01 Standard "Flow Equations for Sizing Control Valves." When a piping system is designed, the pipe size is determined before sizing of the control valve takes place. If the body size of the control valve is less than the adjacent pipe size, the sizing equations need to take into account the effects of the pipe fittings (reducers and/or expanders) used to install the valve in the piping system. The Fp factor is used to account for the effects of these fittings. When sizing a control valve that has a body size less than the inlet or outlet pipe size, the ISA equations treat the valve with fittings as a complete assembly. The Cv and valve critical factors (Fl2, Kc and Xt) are adjusted for the effects of the fittings attached adjacent to the valve. A common misconception is to calculate the Fp factor based on the 100% Cv value of the valve and then apply that factor for all intermediary Cv factors of the valve. This is incorrect. The Fp factor needs to be calculated based on the intermediate (throttling) Cv values. As the valve closes, the effects of the Fp factor diminish, the fluid velocity decreases and the restriction of the valve increases. This causes the restriction of the valve to dominate the system and the restriction of the adjacent fittings to become insignificant in the system. Rotary valves with high Cv values can be greatly affected by the piping geometry (Fp). For globe valves with low Cv values, the effects of Fp are usually insignificant. How are the fluid constant values derived for Saturated and Superheated Steam, and what is the source for the calculations? To size a control valve for Steam, temperature and specific volume are the required fluid constants. For Saturated Steam, equations are used to calculate the temperature and specific volume. The equations were developed by: Gonzalez-Pozo, Virgilio, Formulas estimate properties for dry, saturated steam, Chem. Eng., May 12, 1986 Stoa, Terry A., Formulas estimate data for dry, saturated steam, Chem. Eng., December 10, 1984 For Superheated Steam, Alpha-I currently requires the user to input thevalues for temperature and specific volume. For Saturated and Superheated Steam, the table values were abstracted from "Thermodynamic and Transport Properties of Steam" (Copyright, 1967, by the American Society of Mechanical Engineers.) Why can't I change printers within the Print Dialog Box of Alpha I? This is a recognized problem in a third party software program used by Alpha I. Because of this problem, Alpha I will always print to the default printer set by Windows. Since DeZURIK started using this third party software, the software company was purchased and the new version requires us to pay a license fee of $50 per copy for every program we distribute. We want to continue to offer Alpha I free of cost to our customers, so we find this option unacceptable. We are searching for another software program that will solve this problem and give us an unlimited license. Until that time, the printer designation can be changed by going through the Start/Settings/Control Panel/Printers menu and right clicking on the printer icon to change the default setting.
DeZURIK sizing and selection programs (Alpha I and SmartSize) are provided to customers and potential customers to facilitate sizing of valves and steam conditioning equipment. Any or all of these programs may be loaded on as many hard drives or networks as required by customers to facilitate sizing of equipment without infringing on DeZURIKcopyright in any manner. Printable version of copyright information
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