Physical properties of fluid and fluid transport in piping system

Density, specific volume, specific gravity

Density of fluid mixture

Flow in pipes and valves theory - full content

If the fluid being considered is the mixture of several components, physical properties such as density are calculated based on the property of each component with its volume or mass ratio used. One of fluids that is actually mixture of several components is liquefied petroleum gas or LPG. LPG is mixture of propane (C₃H₈), butane (C₄H₁₀) and other components. The density of such mixture is calculated as defined bellow.

Density of fluid mixture is calculated as:

or

where is:

• &rho _MIX - density of mixture
• i - density of component i
• r_i - volume ratio of component i
• g_i - mass ratio of component i

If volume of each component in the mixture is known, than component volume ratio can be calculated as:

where is:

• r_i - volume ratio of component i
• V_i - volume of component i
• V_MIX - volume of mixture
• n - total number of components

If mass of each component in mixture is known, than component mass ratio can be calculated as:

where is:

• g_i - mass ratio of component i
• m_i - mass of component i
• m_MIX - mass of mixture
• n - total number of components

For known mass ratio, volume ratio of each component is calculated:

or:

For known volume ratio, mass ratio of each component is calculated:

or:

Molar mass of the mixture is:

or:

where is:

• M_i - molar mass of component i
• M_MIX - molar mass of mixture
• g_i - mass ratio of component i
• r_i - volume ratio of component i

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