Patent ID: 8348085

Claim:
A pressure tank, comprising: a metallic vessel including upper and lower shells joined together; the lower shell having a protrusion provided with a stepped hole including a lower cylindrical hole and an upper cylindrical hole of diameter smaller than the lower cylindrical hole and thereby providing a shoulder in the stepped hole; a plastic liner received in the upper shell of the metallic vessel; a diaphragm disposed in the plastic liner; the diaphragm and the plastic liner together defining a storage space therebetween; and the diaphragm and the lower shell of the metallic vessel together defining a pneumatic room therebetween; a through-wall connector secured in the upper shell of the metallic vessel and the plastic liner to communicate the storage space with the outside of the metallic vessel; and a nozzle secured in the lower shell of the metallic vessel to communicate the pneumatic room with the outside of the metallic vessel; the nozzle including a nipple, an anti-leak assembly and a one-way valve; the nipple being at least partly received in the stepped hole of the protrusion of the lower shell and having a protruding section sitting in the lower cylindrical hole of the stepped hole of the protrusion of the lower shell of the metallic vessel; the anti-leak assembly including an O-ring and a connecting member; the O-ring being placed around the nipple and sitting in the lower cylindrical hole of the stepped hole of the protrusion of the lower shell and sandwiched in between the protruding section of the nipple and the shoulder of the protrusion of the lower shell; the connecting member defining a through hole for reception of the nipple and the protrusion of the lower shell of the metallic vessel; the through hole of the connecting member having an upper screw hole for reception of a threaded section of the nipple; and the one-way valve being received in a passage formed in the nipple.