Abstract: A pressure measuring section is arranged between a pipe section connected with an injection pump and a pipe end section or portion. The pressure measuring section is provided with a pressure measuring location which is determined by a measuring chamber arranged internally of a housing portion. Within such measuring chamber or compartment there is located a pressure-impinged portion of a pressure measuring transducer which generates electrical signals in accordance with the pressure prevailing in the injection medium. These electrical signals are inputted by a cable to a signal evaluation location. The measuring location is located in close proximity to an outlet opening of the pipe end portion or section. Between this outlet opening and the pressure measuring location there is arranged a packing device which seals the annular or ring-shaped compartment between the pipe end section and the wall of the borehole.