An extensively validated thermodynamics library with almost 20 years of program refinement

Used for almost two decades by the oil and gas industry, Symmetry Thermo is an accurate predictor of phase equilibria and physical properties for a variety of mixtures.


Run virtually any processing application throughout your well's lifecycle

The result of our work is a thermophysical property calculator with the versatility to monitor the performance of an engine or natural gas well, optimize your natural gas compressors, and improve the safety of the relief valves.

Symmetry Thermo powers the SYmmetry software platform and many other custom software applications. Its unique programming interface gives it the flexibility to embed in any process simulation software or engineering application.

Tried, tested, and true

Relentless testing using experimental data collected and evaluated at the VMG-sponsored Thermodynamics Research Centre in Boulder, Colorado has made Symmetry Thermo the most accurate predictor of phase equilibria and physical properties for many processes used in the industry.

Symmetry Thermo is capable of accurately predicting the behaviour of complex combinations of chemicals. With more than 80 thermodynamic property packages, Symmetry Thermo can model most process systems.

Multi-phase flash system

Symmetry Thermo's multi-phase flash system has a robust material balance and phase stability algorithm.

It calculates the number of phases in your process as well as the composition, amount, and physical properties of the materials in each phase at thermodynamic equilibrium.

Our flash system reliably performs the basic calculations for steady-state process simulators such as VMGSim and dynamic process simulators such as VMGSim and IDEAS.

Beyond process simulation

Symmetry Thermo is continuously validated, giving it the capability to model a wide variety of systems out of the box. It is also configurable and able to handle different specifications for flash calculations.

These features make it the property package system of choice for designing relief valves, compressors, and online monitoring systems.

Build accurate virtual processing models every time

The Thermodynamics Research Centre (TRC), a part of the National Institute of Standards and Technology (NIST) focuses its work exclusively on collecting and evaluating the physical properties of fluids.

VMG was the first process simulation company to join NIST.

Ensure accurate and reliable thermodynamics properties every time

VMGThermo is a set of software components used for the calculation of thermo-physical properties and flash calculations. It's a carefully crafted set of application programming interfaces that are used to power any application that can benefit from high quality physical properties.

VMGThermo includes interfaces for:

  • Visual Basic
  • Delphi
  • Visual C++
  • C
  • C++

If you know how to use a spreadsheet, you can use Symmetry Thermo.

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Symmetry Thermo also ensures reliable and accurate process simulation modelling in the Symmetry software platform.


Symmetry Thermo provides you with a complete set of physical and thermodynamic properties for pure components and mixtures over a wide range of pressures, temperatures, compositions, and phases.

Also included is a comprehensive pure component database with nearly 5,500 pure components, with more than 100 physical properties per component. These include important properties for environmental applications, such as maximum exposure limits, adsorption capacity in activated carbon, and solubility in water.


Symmetry Thermo may be executed from Excel via a VBA interface or a user’s own calculation program as a callable DLL or within the Symmetry software platform. Symmetry Thermo is being used as an operator advisory tool. Symmetry Thermo is also CAPE-OPEN enabled and can thus be interfaced to software at this interface level.

Missing pure component physical properties are automatically estimated using a recommended set of models. Missing interaction parameters for activity coefficient models are automatically estimated using UNIFAC. And all estimated interaction parameters are documented and can be user-inspected.


Get world-class simulation software for a variety of processing applications

  • Production facilities
  • Offshore platforms
  • Gathering systems
  • Fluid properties
  • Gas hydrates
Gas Processing
  • Sweetening
  • Dehydration
  • Sulfur recovery
  • Acid gas injection
LNG Facilities
  • Cryogenic processes
  • Liquefaction
  • CO2 freezing
Oil Refining
  • Crude oil distillation
  • Refinery reactors
Heavy Oil/Oil Sands Process
  • Predicting properties of heavy oil, diluents, and bitumen

Contact Us

To find out how VMG can help you solve your process challenges, email or call in the U.S. and Canada at (403) 457-4595. For all other inquiries, please fill out the form below.

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