mean interstitial velocity of the carrier gas

in chromatography

The interstitial velocity, $u$ of the carrier gas multiplied by the pressure-gradient correction-factor, $j$ :

$u ̄ = u j$

$u ̄ = F j ɛ I$

where $F$ is the nominal linear flow, $ɛ I$ is the interstitial fraction.

Source:

Orange Book, p. 103