VALVE FOR GAS CYLINDER WITH CHECK-VALVE PREVENTING UNOFFICIAL REFILLING

1 . A valve for a gas tank, said valve comprising:

a body comprising:

an engaging portion for sealingly engaging with a gas tank,

a gas inlet,

a gas outlet, and

a gas passage fluidly connecting the gas inlet and the gas outlet;

a shut-off device in the gas passage;

a check-valve comprising:

a check-valve seat in the gas passage;

a check-valve obturator configured for contacting the check-valve seat and thereby closing the gas passage in the presence of a refill gas flow from the gas outlet to the gas inlet;

wherein the check-valve seat is resiliently urged against the body and configured to move away from the body so as to open the gas passage when subjected to a refill differential pressure reaching a predetermined threshold.

2 . The valve according to claim 1 , wherein the gas passage extends longitudinally in the body, the check-valve seat being configured for opening the gas passage in a radial direction.

3 . The valve according to claim 2 , wherein the check-valve seat is movable longitudinally.

4 . The valve according to claim 3 , wherein the check-valve seat comprises a cylindrical sleeve slidingly received in a housing attached to the body.

5 . The valve according to claim 4 , wherein the check-valve comprises a spring located in the housing and resiliently urging the check-valve seat against the body.

6 . The valve according to claim 4 , wherein the housing comprises a cylindrical wall with radial passages for the refill gas flow.

7 . The valve according to claim 6 , wherein the radial passages are closed by the cylindrical sleeve when the check-valve seat is against the body and are opened when the check-valve seat is moved away from the body.

8 . The valve according to claim 6 , wherein the cylindrical wall of the housing comprises a thread engaging with a corresponding thread on the body.

9 . The valve according to claim 1 , wherein the check-valve seat comprises a hole forming the gas passage through the check-valve seat, to be closed by the check-valve obturator.

10 . The valve according to claim 1 , wherein the check-valve seat comprises a gasket contacting in a gas tight fashion an inner surface of the body, when the check-valve seat is resiliently urged against the body, the gasket being away from the inner surface of the body when the check-valve seat is moved away from the body.

11 . The valve according to claim 10 , wherein the check-valve seat comprises an outer surface with longitudinal recesses extending from the gasket towards the shut-off device.

12 . The valve according to claim 1 , further comprising:

an excess flow valve seat in the gas passage, opposed to the check-valve seat and configured for being contacted by the check-valve obturator so as to close or reduce the gas passage in the presence of a service gas flow from the gas inlet to the gas outlet that reaches a predetermined excess flow.

13 . The valve according to claim 12 , wherein the excess flow valve seat is formed by a circular hollow and stepped element inserted into a bore of the body on the gas inlet side.

14 . The valve according to claim 13 , wherein the circular hollow and stepped element comprises at a proximal end thereof an inner surface slidingly receiving a pin of an obturator of the shut-off device, the proximal end supporting a spring urging the shut-off device obturator towards a seat of the shut-off device.

15 . The valve according to claim 13 , wherein the circular hollow and stepped element comprises a distal end adjacent a ring housed in an inner groove in the bore of the body and holding the circular hollow and stepped element in the bore.

16 . The valve of claim 1 , wherein the predetermined threshold is comprised between 8 and 17 bar.