The research results presented in this article are a continuation of extensive research on new materials for hydraulic elements, which are intended to be part of new “green” hydraulic drives. One of the greatest advantages of polymer materials in hydraulic systems is the possibility of cooperation with water as a working medium, which can help in the gradual reduction of fossil fuel extraction. As a result of preliminary research on the shaping of poppet-valve pair in lift valves and modeling of flow in small gaps, the question arose whether the material of the valve poppet can affect the flow characteristics. This article presents the results of numerical and experimental studies of determining the pressure-flow characteristics of a lift valve, taking into account different materials of the valve poppet. The flow characteristics were determined for two liquid temperatures, a lift height of 0.25 mm, and three different poppet materials. The differences in the obtained results were analyzed in detail.