Constants
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Introduction
There are a number of constants used in SysCAD in calculations, models or the solver. Wherever possible the references used are obtained from NIST website.
Conversions
For constants used in converting between different units of measurement see Conversion Factors.
- Reference: NIST - Guide for the Use of the International System of Units (SI) (NIST Special Publication 811 2008 Edition, Ambler Thompson and Barry N. Taylor).
Molecular Weights
The Standard Atomic Weights are used to define the molecular weight of species. Please see Species Definition.
Prior to Build 139: The Standard Atomic Weights are from NIST web site.
- Reference: Standard Atomic Weights. Reference NIST Version 3.0 July 2010 (M.E. Weiser, M. Berglund, et al).
From Build 139: The Standard Atomic Weights for the following elements have been updated using latest information from the IUPAC website.
Al, As, Au, Be, Cd, Co, Cs, F, Ge, Hf, Hg, Ho, Mn, Mo, Nb, P, Pr, Rh, Sc, Se, Tb, Th, Tm, Y, Yb
- References:
Other Constants
Some other constants used in SysCAD.
| Constant | Value | Units | Reference |
|---|---|---|---|
| Gravitational Constant | 9.80665 | m/s2 | NIST |
| Universal Gas Constant | 8.314472 | J/mol K | NIST |
| PI | 3.14159265358979 | ||
| Standard Temperature | 25.0 | °C | |
| Standard Pressure | 101.325 | kPa |
Use in PGM
Constants can be accessed directly in MP and PGM code. See Predefined Constants.
For molecular weights use PGM Species Database Class and MW() function.