Hydrostatic seals are non-contacting seals in an equilibrium of forces even at the speed n = zero. On account of the applied pressure differential, medium flows through their shaped sealing gap. If the pressure differential falls below the minimum value (prescribed by the design), the non-contacting ceases.  

The functional principle means that hydrostatic seals must have leakage flows some 10³ times higher than the leakage of a hydrodynamic seal. The main advantage of the hydrostatic seal is its ability to reduce high pressures in a single stage. Its extreme sensitivity to solids is a disadvantage.