In this work, the mass transfer of a model volatile organic compound through silicone rubber membrane tubes has been investigated for the transition between laminar and turbulent flow regimes. Results showed that a flow transition region occurred over the expected Reynolds number range, from 2300 to 5500. Two correlations have been established for flow during transition and early turbulence: Sh = 1.1 Re-0.35 Sc-0.33, for 2800 < Re 5500, and Sh = 0.010 Re-0.93 Sc-0.33, for 5500 < Re < 10,000. A cost analysis showed that significant reductions in total costs are obtained for operating conditions in the nonlaminar regime, although membrane burst pressure may prevent working at cost optimal Reynolds numbers.