# Pipe Flow Gasref App - Results Data

Tapping**CALCULATE GAS DATA**displays the following gas property data for the selected gas at the specified temperature and pressure condition.

## Density (From the Ideal Gas Law)

For a specific temperature and pressure condition the compressed density of a gas can be calculated using the Ideal Gas Law

At a higher presure condition the gas density will increase; the same mass (weight) of gas will be compressed in to a smaller volume. At a higher temperature condition the same mass (weight) of gas will expand to an increased volume and hence this will result in a lower gas density.

Calculating the Density using the Ideal Gas Law gives a good approximate result for most gases, provided that the gas does not significantly deviate from the ideal gas law line at high pressure conditions.

## Compressibility Factor Z

The Pipe Flow Gasref software can calculate and display the compressibility factor of certain gases at different temperature and pressure conditions.

The compressibility factor corrects for the differences between the real gas density at a high pressure condition and those predicted by the Ideal Gas Law.

## Real Density

In addition to the calculating the density from the ideal gas law, the Pipe Flow Gasref App will also calculate and show the real density of the gas at the specified condition, taking account of the Z Compressibility Factor.

## Viscosity

Viscosity is the fluid's resistance to flow, which is caused by a shearing stress within a flowing fluid and between a flowing fluid and its container.

A fluid viscosity can be described by its Dynamic viscosity (sometimes called Absolute viscosity), or it's Kinematic viscosity. These two expressions of viscosity are not the same, but are linked via the fluid density.

Kinematic viscosity = Dynamic viscosity / fluid density

Centipoise (cP) is commonly used to describe dynamic viscosity.

Viscosity is only weakly dependent on pressure and varies mainly with changes with temperature.

## Specific Heat Ratio

The Specific Heat Ratio (also known as the adiabatic index or the heat capacity ratio) is the ratio of the heat capacity at constant pressure to heat capacity at constant volume.