| 摘要 |
To safeguard conduits carrying a pressure medium, especially water, oil or oil-in-water emulsions, a shut-off valve is provided which has a piston, loaded by a compression spring, in a tubular housing. This housing has an internal throughhole in which the compression spring and the piston are arranged axially relative to one another. The piston itself is designed as a stepless, smooth cylinder and provided with two blind holes extending in opposite directions which, in the region of a channel surrounding the piston, have radial holes, allowing the pressurized liquid to pass from one blind hole into the other when the piston is in a corresponding position. This position is determined, on the one hand, by the compression spring and, on the other hand, by the pressure ratio on the two sides of the piston. If this pressure ratio changes, for example due to the rupture of a hose, the force of the compression spring is no longer sufficient to hold the piston in the open position, and the shut-off valve closes off the passage for the pressure medium rapidly and reliably. <IMAGE>
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