An automatic gas purge valve comprising a first housing (20, 220) configured with an automatic gas purge valve system comprising: - a normally closed gas discharge faucet (100, 300) having a control chamber (132, 332), said gas discharge faucet (100, 300) being configured with a fluid inlet port (112, 312) being in flow communication with the first housing (20, 220) and a fluid discharge port (140, 340) configured for discharging gas at substantially high flow rates, and - an automatic valve unit (46, 246) having a second housing (60, 260), an inlet port (66, 266) in flow communication with the first housing (20, 220) and an outlet port (68, 268) being in flow communication with the control chamber (132, 332), and configured for selectively generating a flow pulse at the control chamber (132, 332) to displace the gas discharge faucet (100, 300) into its open position, wherein the automatic valve (46, 246) is manipulable between a closed position and an open position responsive to liquid level within the first housing; characterized in that said automatic valve unit (46, 246) is configured with a flexible closure membrane (76, 276) secured at one end (80, 280) to the second housing (60, 260) and at an opposite end (82, 282) to a membrane displacing member (84, 284) which is axially displaceable within the second housing (60, 260) responsive to the liquid level; and in that displacement of said membrane displacing member (84, 284) in a downwards sense progressively detaches successive transverse portions of the flexible closure membrane (76, 276) so as to open the outlet port (68, 268) towards the open position of the automatic valve unit (46, 246). - a normally closed gas discharge faucet (100, 300) having a control chamber (132, 332), said gas discharge faucet (100, 300) being configured with a fluid inlet port (112, 312) being in flow communication with the first housing (20, 220) and a fluid discharge port (140, 340) configured for discharging gas at substantially high flow rates, and - an automatic valve unit (46, 246) having a second housing (60, 260), an inlet port (66, 266) in flow communication with the first housing (20, 220) and an outlet port (68, 268) being in flow communication with the control chamber (132, 332), and configured for selectively generating a flow pulse at the control chamber (132, 332) to displace the gas discharge faucet (100, 300) into its open position, wherein the automatic valve (46, 246) is manipulable between a closed position and an open position responsive to liquid level within the first housing; characterized in that said automatic valve unit (46, 246) is configured with a flexible closure membrane (76, 276) secured at one end (80, 280) to the second housing (60, 260) and at an opposite end (82, 282) to a membrane displacing member (84, 284) which is axially displaceable within the second housing (60, 260) responsive to the liquid level; and in that displacement of said membrane displacing member (84, 284) in a downwards sense progressively detaches successive transverse portions of the flexible closure membrane (76, 276) so as to open the outlet port (68, 268) towards the open position of the automatic valve unit (46, 246).