For process analysis, reliability is one of the most important aspects. Automatic stream switching is necessary for automatic calibration and other operations. Many people may say it can be easily done with a rotary selection valve, but, things are not as simple as they might thought. In the conventional configuration of rotary valves for stream switching (sucking liquid from different channels), the pressure of the liquid in the valve is lower than that of the atmosphere, the air tends to leak in (from the contact surface between the rator and the stationary base), especially for those of poor quality. Additionally, the dissolved air also tends to resurface under lower pressure. To solve above problems, we proposed the valve-based and pump-based configurations for reliable stream switching configurations in which the pressure of liquid in the valve is higher than that of the atmosphere.