ChemSOF is being developed to provide chemical engineering calculations alongside explanations of their methods, inputs, and limitations. This page describes the approach intended for developing and checking those tools.
Each calculator has its own scope. A simple equation may require a small set of checks, while a calculation involving numerical iteration, property data, or multiple operating conditions may need a broader review. The method and checks relevant to a tool should be documented as that tool is prepared for publication.
Defining the Calculation
Development begins by identifying the question the calculator is intended to answer. Its scope should describe the required inputs, the expected outputs, and the situations in which the selected method is applicable.
The specification should also identify:
- Equations and methods, including the definitions of their variables.
- Assumptions, such as the treatment of fluid properties or operating conditions.
- Units and calculation basis, including supported input and output units.
- Validity limits, including the conditions and ranges stated for a correlation or model.
- Sources, including references for equations, coefficients, and property data.
A calculator should explain its scope clearly enough for readers to judge whether it is relevant to their problem.
Selecting Sources and Data
Methods and data may come from textbooks, technical literature, reference databases, standards, or other suitable sources. A source should be checked for its context and applicability before it is used.
Physical properties and correlation coefficients depend on their definitions and conditions. When they are used, the relevant temperature, pressure, phase, units, and range of applicability should be considered. The same property can have different values under different conditions.
Where a calculator uses a third-party library or dataset, its documentation and applicable usage conditions should also be considered. A model’s availability does not establish its suitability for every fluid or process.
Implementation and Unit Handling
The calculation method is translated into software that accepts the stated inputs and returns results in the selected units. Unit conversions should be checked alongside the engineering equation, including distinctions such as absolute pressure and gauge pressure or temperature and temperature difference.
Input checks should help identify missing, inconsistent, or unsupported values. Where a method cannot produce a meaningful result for the supplied conditions, the tool should communicate that limitation rather than present an unexplained answer.
Verification and Validation
Verification and validation address related questions. Verification considers whether the method has been implemented as intended. Validation considers whether the calculation is suitable for its stated purpose and conditions.
Checks are selected according to the calculator and may include:
- Comparing results with independent hand calculations or suitable published examples.
- Testing equivalent inputs expressed in different supported units.
- Checking boundary conditions, limiting cases, and invalid inputs.
- Checking intermediate values and the consistency of balances.
- Testing convergence and numerical behavior where iteration is used.
- Confirming that properties and correlations are used within their stated scope.
- Repeating relevant checks after a change to code, data, or equations.
Reference examples and comparisons must use compatible assumptions, units, and input conditions. Agreement with another tool can be informative, but it is not a substitute for understanding the methods and data behind both results.
Worked Examples and Technical Review
Where practical, ChemSOF aims to provide a worked example that identifies the problem, inputs, calculation steps, and result. An example should correspond to the method and settings described on the calculator page.
A person with knowledge appropriate to the subject should review the calculation’s method, implementation, explanation, and test evidence before release. The scope of review should match the complexity of the tool. ChemSOF should identify reviewers or describe the review performed only when that information is accurate and available.
Versions, Updates, and Corrections
Calculators may change when methods are clarified, errors are corrected, data is updated, or features are improved. Changes that affect results should be documented with the relevant version and tested against appropriate reference cases.
If a potentially significant error is identified, the affected calculation should be investigated. Depending on the issue, an appropriate response may include correcting the tool, adding a notice, or temporarily making it unavailable while the issue is assessed.
Readers can help by reporting a suspected problem through the Contact page. Please include the calculator name or URL, input values and units, the result observed, and any expected result or reference. Do not include confidential plant or process information in a report.
Using ChemSOF Calculators
ChemSOF calculators are intended to support learning, calculation checks, and preliminary estimates within each tool’s stated scope. A result depends on the information supplied, the selected method, the quality of the underlying data, and the assumptions made.
Users remain responsible for assessing whether a method applies to their situation, checking results independently, and following the applicable requirements and engineering review procedures for their work.
Related Information
For more about ChemSOF’s approach to sources, corrections, and AI-assisted work, see the Sources & Data Policy, Corrections Policy, and AI Policy when available.
This page may be updated as the project’s development and review processes evolve.