Volumetric thermal expansion takes place in gasses and liquids when a change in temperature, volume or type of substance occures.
\(\Delta V = 3 \alpha V_i \Delta T \)
\(\Delta V = \beta V_i \Delta T \)
\(\Delta V\) = volume differential
\(\beta\) = volume thermal expansion coefficient
\(V_i\) = initial volume
\(\Delta T\) = temperature differential