Patent ID: 7575710

Claim:
A gas flow control system for a gas fuelled torch, comprising: a first fluid passage having a first inlet adapted to be connected to an external fuel gas source and a first outlet adapted to be connected to the gas fuelled torch; a second fluid passage having a second inlet adapted to be connected to an external oxygen source and a second outlet adapted to be connected to the gas fuelled torch; a first on-off valve in the first fluid passage controllable only between a fully open position and a closed position; a second on-off valve in the second fluid passage controllable only between a fully open position and a closed position; a first bypass passage in fluid communication with the first fluid passage, bypassing the first on-off valve; a third on-off valve in the first bypass passage controllable only between a fully open position and a closed position; a second bypass passage in fluid communication with the second fluid passage, bypassing the second on-off valve; a fourth on-off valve in the second bypass passage controllable only between a fully open position and a closed position; and a control apparatus having physical links to the respective on-off valves for selectively and simultaneously actuating the individual first, second, third and fourth on-off valves in different combinations, thereby forming a first operational mode wherein all passages are closed, a second operational mode wherein the first and second fluid passages are open, and a third operational mode wherein the first and second fluid passages are closed and the first and second bypass passages are open.