This is a proven design principle in which the chemically resistant, low-friction jacket made of polytetrafluoroethylene or ultra-high-molecular-weight polyethylene is energized by a stainless steel spring. This gives the U-cup seal elasticity, provides a low initial contact force, and allows the sealing force to increase with system pressure. Low-friction designs are possible, as are applications at high pressures exceeding 1,000 bar. Thanks to machining, there are virtually no limitations on diameters, profile cross-sections, or other design features.
A disadvantage is the resulting dead space.
