| 摘要 |
<p>Pneumatic or hydraulic conduits which form a protection against intruders, are connected to a detector which registers a possible variation of the pressure and sets off an alarm. With a view to preventing an interruption, for example, by crashing of the conduits, said conduits comprise a core (2) made of hard and resistant material, for example one or a plurality of steel wires and preferably a steel cable. Upon a crushing attempt inner channels remain (4) due to the limited capacity of extrusion of the core and pressure variations may be sensed by the detector. These conduits are used for making networks which are under pressure and may be used as sensors for the peripheral protection or as a protection for doors or stores. They form an obstacle against the penetration into a space or a local thus protected, which may be entered only after previous destruction. The resulting leak causes a pressure drop and consequently the setting off of the alarm. </p> |
