series between a process fluid and an environment and a barrier fluid arrangement to provide a barrier fluid to spaces formed between the sealing elements the barrier fluid arrangement has at least two compensator devices where under use the pressure in the process fluid is acting on one side of a piston in the compensator device and the pressure in the barrier fluid is acting on the opposite side of the piston there is a difference between cross sectional areas of the two sides of the piston and the difference varies between the at least two compensator devices application_number US 201013201739 A description hereafter embodiments of the invention will be described in embodiments of the invention numerous specific details are set forth in order to provide a more thorough understanding of the invention however it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details in other instances well known features have not been described in detail to avoid obscuring the invention in fig1 there is shown an elevated sketch of a drill pipe 1 forming the rotating element with a washpipe 3 forming the stationary element attached to the drill pipe 1 there is in the drill pipe 1 indicated another inner pipe 6 between the drill pipe 1 and the inner.