An experimental research project was conducted to evaluate the pressure transient levels and time to system equilibrium generated in a regulated liquid propulsion system due to system activation. This was accomplished through the development of a propulsion system experimental setup utilizing gaseous nitrogen as the pressurant and distilled water as a propellant simulant for hydrazine. A common liquid reservoir was used as the propellant tank and high-pressure gas was regulated to beginning of life conditions. To protect the regulator from high-pressure trnsients, a snubber orifice was installed upstream of the regulator. Numerous experiments were performed evaluating bottle pressure, tank pressure, snubber orifice diameter, and system volume. Based upon experimental results, a mathematical model was created to predict activation time for regulated propulsion systems given initial conditions. Experimental results are presented along with the propulsion system activation time model.