Safety device for pressurized gas

A safety device forming a relief valve that releases a gas under pressure in the event of a dangerous situation, the safety device comprising

• a) a body defining a channel (1, 2) configured to be capable of directing a flow of gas in a longitudinal direction between
• A) an upstream first end (11) adapted to be placed in contact with a source of gas (G) under pressure and
• B) a downstream second end (12) adapted to be placed in contact with the exterior atmosphere,
• b) a plug (3) situated on the channel (1, 2) configured to prevent a gas from flowing between the upstream end (11) and the downstream end (12) under normal situations, the plug (3) being configured to open the passage to the gas when subjected to a pressure and/or temperature that exceed a determined threshold,
• c) wherein, from upstream to downstream, the channel (1, 2) comprises two adjacent flow portions, these respectively being an upstream and a downstream flow portion, the respective transverse dimensions (d, D) of which are different, with a ratio (D/d) between the transverse dimension D of the downstream portion (2) and the transverse dimension d of the upstream portion (1) being from 1.4 to 11;
• d) wherein a junction between the two adjacent portions (1, 2) forms a discontinuity in the transverse dimension of the channel (1, 2), with a ratio (L/D) between the length L of the downstream portion (2) and the transverse dimension D of this downstream portion (2) being from 5 to 100.