The primary rotary seal face rotates at the same speed as the pump shaft while maintaining equally distributed seal face loading. Mechanical rotary seal face compression is generally accomplished by incorporating a single coil spring, bellows, or multiple spring arrangement within the respective seal design.
Mechanical seals using a single coil spring have a wide range of applications.
Such seals feature a simple, easy to use design with large spring cross sections which resist corrosion. Its chief limitations are its tendency to distort at high surface speeds and the large axial and radial space it requires within the pump stuffing box. High speed centrifugal pump applications prohibit the use of single coil springs as high rotational speeds promote distortion of the rotary seal face which may induce excessive fluid leakage. Applications of this nature can incorporate a number of small coil springs spaced around the rotary seal face unit. These small springs are not as susceptible to distortion at high speeds as is the single coil spring, and they consequently exert an even compression on the seal face at all times.