The diameter of the shaft is 20 mm, and the circumferencial speed is 1,5 m/s, which i calculated doing
velocity = angular speed * shaft radius
The shaft rotates at 1370 rpm.
The graph should give the permissible speeds for the shaft to rotate at that allow the use of the simmerring made of that material. NBR and FKM are two materials from which their simmerings are made.
Source: http://www.simrit.com/files/00001387.pdf , p.20