Abstract: A shut-off device, such as a valve or a cock, for pipelines and comprising a casing provided with a flow passageway. The casing is provided with an inlet and an outlet and at least one shut-off member provided with a cavity, the member being movable between a position in which the flow passageway is open and a position in which the flow passageway is closed. An auxiliary chamber is arranged in the casing and communicates with the cavity of the shut-off member. The auxiliary chamber is defined by a separate, almost non-resilient wall portion abutting an abutment face on the wall of the casing. A pressure-relieving passageway formed in the wall of the casing is arranged between an abutment face at the auxiliary chamber and the inlet or outlet of the shut-off device. As a result, a shut-off device having more simple structure than known shut-off devices is obtained.

Abstract: A shut-off device of the double block-and-bleed type comprising a flow passageway accommodating two shut-off members provided with through-going cavities, and a drain means. The flow passageway is provided with an inlet and an outlet. Each of the shut-off members may be moved between a position in which the flow passageway is open and a position in which the flow passageway is closed. In association with the shut-off members two auxiliary chambers are communicating with cavities of the shut-off members. The shut-off device is formed of a single undivided casing. The shut-off members are truncated cone-shaped and mounted in matching truncated cone-shaped recesses in the common casing. As a result, the overall length of the shut-off device may be reduced compared to prior art. Moreover, the tightness at high pressure, e.g. above 100 ato. is enhanced.