A new gas delivery system is being designed to inject either tritium or deuterium gas with uniform throughput for up to 6 seconds into the TFTR Neutral Beam Long Pulse Ion Sources. Several experiments have been conducted to verify design concepts and qualify components. Piezoelectric valves were characterized for hydrogen and deuterium gas and the data used to predict operation with tritium. The uniformity of the gas throughput was studied as a function of test fluid, flowrate and initial plenum pressure. Various passive techniques to mitigate unacceptable thermal effects were tested. The uniformity of the throughput with an active pressure feedback controller was tested under various operational scenarios. The functionality of a prototypical NB D-T Gas Delivery System has been analyzed. This paper presents the results of these pre-operational tests.