Propane in liquid state is mostly pumped under pressure and at approx. 90 K. Used as an energy source, propane has many applications, including propulsion in orbital rockets. We have developed labyrinth seals, gap seals and mechanical seals for this application. Here, the material selection to be used is eminently important to ensure reliable operation. Specially developed hydroseals as segmented sealing rings are suitable for sealing the application during standstill and rotation during operation. During rotation and the pressure build-up, the centrifugal forces of the medium cause the propane seal to open slightly, creating a low-friction sealing gap between the shaft and the static seal. This allows the propane to be selectively reduced in pressure and flow through the sealing gap in a reduced mass flow. At standstill, the seal contracts again and seals radially to the shaft. Attention must be paid to the surfaces of the shaft and the surface of the propane seal. A dynamic propane seal is designed as an axial seal. In this case, attention must be paid to the heat input of the hydraulically supported seal. Low leakage can be achieved by using mechanical seals for liquid propane. The propane is sealed by the mechanical seals and safe operation is thus ensured. At cryogenic temperatures, an important component is the correct choice of secondary seals.