Safety valve arrangements, with which a space of a technical facility which is under pressure is connected to two safety valves connected in parallel, via a shuttle valve which is serially connected in front of the two safety valves form the basis of the invention. For this, the shuttle valve has two fluid outlets, on which one of the two safety valves is arranged in each case, and selectively closes one of the two fluid outlets and thus the flow path to one of the two safety valves. Accordingly, only one of the safety valves is envisaged for relieving an unallowably high pressure in the space subjected to pressure, which e.g. can be a container or pipe conduit. This relief of the pressure is effected by way of a part of the fluid located in the space being let off via this safety valve until an allowable pressure prevails in the space again. The second safety valve merely forms a redundancy in the case of a defect of the first safety valve and then assumes its function after a corresponding switch-over. The shuttle valve moreover permits service or repair work on the safety valve which is not in flow connection with the space, wherein the safety of the space subjected to pressure is ensured with a full availability of the technical facility on account of the other safety valve.
Such shuttle valves on which the two fluid outlets are arranged on a valve housing lying directly opposite one another belong to the state of the art, wherein a shut-off body arranged between the fluid outlets can be linearly displaced in a manner such that it closes either the one or the other fluid outlet. With such shuttle valves, it has been found to be a problem that on account of the arrangement of the fluid outlets on the valve housing, the flow path is designed in a manner such that it can lead to flow losses or pressure losses in the shuttle valve. These flow losses or pressure losses in turn can have the effect that the safety valve serially connected subsequently to the non-closed fluid outlet possibly no longer correctly fulfils the envisaged function in the case of an overpressure in the space to be protected.
Moreover, shuttle valves comprising a rotatably mounted shut-off body which by way of a rotary drive can be rotated in a manner such that a flow channel running through the shut-off body creates a flow connection of the fluid inlet to one of the fluid outlets are known. Given a suitable design, as a rule favorable flow conditions prevail in these shuttle valves. However, with such shuttle valves, it has been found to be disadvantageous that their manufacture is generally very complicated and thus expensive, above all due to the necessary sealing of the shut-off body with respect to the valve housing. Moreover, soft-sealing materials limiting the application conditions (temperature, media resistance) are often necessary for the sealing.