Air supply apparatus for air jet loom

The air supply apparatus includes a compressed air supply source (14); a first switching valve (30) connected with the compressed air supply source; at least one of first compressed air regulators (16, 58, 138, 140) connected with the first switching valve, in which at least one of the outflow quantity and the pressure of compressed air is set at a predetermined first set value; a second compressed air regulator (18, 68) connected with the compressed air supply source, wherein at least one of the outflow quantity and the pressure of compressed air is set at a second set value different from said first set value, the number of said second compressed air regulator being made equal to that of the first compressed air regulators; and a second switching valve (34, 62, 150, 152) connected with said first and second compressed air regulators, wherein the number of said second switching valves is made equal to or more than that of said first compressed air regulator. The second switching valve is connected with main nozzle (12, 50, 124, 126). The first switching valve is opened in a predetermined first period at the weft inserting time, and the second switching valve is opened in said first period as well as in the second period different from said first period.