The Diverter incorporates a self - actuating or stretch fit stripper element, the inside diameter of which seals around the Drill String while mounted on a Bearing Assembly.
The inside diameter of the Stripper Element is smaller than the outside diameter of the Drill String - therefor a stretching takes place to ensure a tight seal.
Well bore pressure that may exist will apply vector forces against the cone shaped profile of the stripper element, thus self - activating.
The greater the wellbbore pressure the greater the pressure on the sealing interface with the Drill String - no external hydraulic pressure source is required for sealability. The passive style of Diverter has been the industry standard for many years and has been proven to be reliable under varied drilling conditions.
Initial training in the use of this system is required, thereafter service people are not needed, unless specifically requested by the client. The passive system is not labour intensive and is therefor more economical in marginal operations.