Chemical database

Overview

The chemical database used in both EFFECTS and RISKCURVES is a comprehensive database of meticulously evaluated data on key chemical compounds used in industrial processes. The chemical database sources information from DIPPR, AIChE's Design Institute for Physical Properties. DIPPR is a licensed database covering over 2000 chemicals and is particularly noted for its focus on non-ideal gas behaviour such as compressibility.

Importance

The chemical database is crucial for determining the consequences of accidental releases in industrial settings. Accurate assessment of these consequences depends on the diverse thermodynamic properties of chemicals, which influence toxicity, flammability, density, state, and volume percentage. Key properties necessary for precise evaluations include (among others) molar weight, lower flammability limit (LFL), boiling point, and vapour pressure.

Key features

The DIPPR (2015) chemical database includes over 2000 extensively validated chemicals and sample mixtures. It offers a wide range of physical and thermodynamic property data, ensuring high accuracy and reliability. Users benefit from the ability to modify properties and create their own mixtures, enhancing flexibility for specific applications. The database supports standardised data formats making the DIPPR database an invaluable resource for precise consequence modeling and risk assessment.

In cases where modifications to chemicals, mixtures, or substances are necessary, the database offers the ability to store copies of existing entries, modify chemical properties, and add mixtures in a separate "user-defined database." This feature allows for essential adjustments to be made to any of the numerous properties as required.

Limitations 

• Mixture property calculations

  • Binary interactions, chemical reactions, absorption effects, and solubility effects are not considered when calculating mixture properties.

  • For pool evaporation, all the components of the mixture are assumed to start evaporating simultaneously at the calculated mixture-based normal boiling point (which are calculated using different equations of state).

  • During dispersion calculations, the composition of the liquid in the pool is assumed to match the composition of the dispersing vapour.

• Equation of state

  • Properties of mixtures are calculated based on a quadratic equation of state that includes compressibility based on the second virial coefficient. 

  • This accounts for non-ideal gas behaviour even though super-critical conditions may yield unreliable results. 

Practical use

In practice, this chemical database allows users to:

• Perform accurate risk assessments and consequence analysis by leveraging a wealth of chemical property data.

• Customise the database to include user-defined chemicals and mixtures, adapting to specific industrial needs.

• Understand the limitations and assumptions inherent in mixture property calculations to interpret results correctly.

By maintaining a robust and adaptable chemical database, EFFECTS and RISKCURVES support comprehensive and precise safety evaluations essential for industrial process management.