Single spring mechanical seals with o-rings are designed with two seal rings/faces with one interface and the pressure of the seal faces not well-distributed  even for the large shaft sizes.The materials for seal rings or faces can be carbon/ceramic,carbon/sic,sic/sic,tungsten carbide/tungsten carbide,ssic/ssic and so on depending on the sealing fluids.The stationary mating ring is secured to a pump housing and the rotary face rotates with the pump shaft and runs against the mating face with a stable flowing film on the interface between the seal face and the mating ring and the rotary parts with elastic spring components move axially in a flexibly to have a proper contact with the stationary face to have a thin and stable flowing film to keep pumps from leakage.