| 摘要 |
The invention relates to a pressure calibration pump apparatus for generation of vacuum or pressure. The apparatus comprises a cylinder (1) with an outlet valve (20) and a displaceable piston (2, 10) operable by means of a piston rod (7). The forward end of the rod carries a conical inlet valve (4, 5, 6) located at the centre of the piston and being provided with channels (8, 12) for supply of a calibration medium. The piston rod and the piston are interconnected in such a way that the alteration of the direction of movement of the piston rod at the respective turning point of the piston movement, involves the opening and closing respectively of the inlet valve (4, 5, 6). For the purpose of generating high pressure or vacuum, the cylinder (1) is provided with sealing means (11) for sealing between the intake side of the piston (2) and the external atmospheric pressure. |
