Professional Engineering Computations introduced VacTran vacuum calculation software some 18 years ago. The current version, VacTran 3, both continues the traditional calculations and siginificantly advances the program's capabilities.
As the pressure decreases during the pump down of any vacuum vessel, the flow regimes through chamber and ducts change from continuum, through transitional, to molecular flow. As the flow changes so do formulas for conductances and pumping speeds. Further complicating this picture is the outgassing rates of various materials which decay exponentially with time. Modeling these interactions, even with a spreadsheet doing the math, is tedious and rarely attempted. VacTran 3is a fast, convenient way to perform a variety of calculations at the 'what-if' design stage to investigate and maximize a vacuum system's performance.
With VacTran 3's easy-to-use interface, the designer can readily adjust any parameter knowing that the appropriate formulas will be applied automatically to allow her/him to:
- Calculate a chamber's pump down time with gas loads
- Model conductance elements and determine their effect on the pumping speed from the chamber
- Compare conductances
- Enter raw data for gas loads or use the outgassing rate library of literature values
- Model the outgassing of multiple surfaces, permeation through o-rings, and known gas flows into the chamber
- Compare the gas loads from these sources
- Create professional-looking graphs
- Avoid vacuum 'surprises'
The major new features in VacTran 3 include:
- Digitizer that accepts a pumping speed curve image and lets the user 'point and click' to build the curve for the pump library
- Six stations for different pump / conductance combinations on any one system
- Calculation of conductances that are: circular, annular, elliptical, trangular, rectangular, conical, and slit- or orifice-shaped
- Calculation for chamber volumes / surface areas: box, sphere, bell jar, cylinder, torus, 4-way and 6-way intersections and crosses, etc
- A gallery to which calculated curves can be automatically saved
- An option that graphs the rate of pressure rise expected during 'leak back' checks
- An excellent interactive e-Help manual that provides valuable vacuum technology training
Our extensive practical experience (almost daily use for 17 years) with all versions of the VacTran program have convinced us of its practicality and utility for vacuum system modeling.
Current VacTran users with version 2 that have parallel port (LPT1) keys can upgrade to version 3 (with USB key) by directly contacting firstname.lastname@example.org. KJLC does not supply this upgrade.