Abstract: The TRIUMF 500 MeV cyclotron delivers proton beam currents up to 100 μA into a dedicated beam line and target system for the production of radioactive ion beams (ISAC). Various radioactive species are produced in the target, which are then ionized and extracted. The ions pass through a mass separator and are transported via a low energy beam transport line to experimental areas or injected into an RFQ accelerator. The existing 14m section of the transport line is pumped by two 500 l/sec, and one 1000 l/sec turbo pumps to achieve an average beam on operating pressure of better then 3.0E-7 Torr. The calculated vacuum required to reduce beam losses due to ion collisions with the residual gas to 0.1%/m for high charge state ions is 2.0E-8 Torr. The outgassing rates for some materials used in the beam lines have been measured at TRIUMF and compared with available tabulated data. In the order to improve the vacuum in the beam line section with the highest outgassing rate a cryopump was installed and vacuum change monitored. A bake out test of a beam line section is also scheduled. This paper reports on the results from the vacuum improvement tests and some related calculations.