@Air provides thermodynamic and transport properties for moist air.  It is based on the formulations developed by the National Bureau of Standards (NBS) for the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE). Techware Engineering has made some improvements to the formulations and extended the database to cover higher temperatures and pressures. The @Air package includes DeskTop Air, the advanced air property calculator.

@Gas provides thermodynamic and transport properties for a mixture of gases including Nitrogen, Oxygen, Argon, Carbon Dioxide and Water Vapor. These five gases account for 99.997% of the volumetric composition of standard air and better than 99.9% of the combustion products of most fossil fuels. @Gas uses  formulations similar to those of @Air along with a database developed by Techware Engineering to provide accuracy in the range of pressure and temperature covered by this product. The @Gas package includes DeskTop Gas, the advanced gas property calculator.

XLInterp is a different type of product from the three described above. It includes a library of functions used to extract numerical information from data tables. These tables may represent properties for other fluids not covered by the products above, equipment performance curves or even financial data. The functions use a process known as interpolation (either linear or non-linear) to extract information from the tables and can work in two dimensions. The real power of XLInterp stems from its ability to interpolate both forwards and backwards. See the product introduction for more information. XLInterp only works with the Excel spreadsheet and has no calculator associated with it.

WinSteam is our most popular product and has become the industry standard for thermodynamic and transport properties of steam and water.  It uses the latest industrial formulations (IAPWS IF97) developed by the International Association for the Properties of Water and Steam (IAPWS) and adopted by the American Society of Mechanical Engineers (ASME). It also allows the use of the previous formulations (IFC 1967) to analyze products developed using those properties. The WinSteam package includes DeskTop Steam, the advanced steam property calculator.