As described above, in the procedures of switching to a reductive operation, after the flow rate of the product gas is reduced by the flow control valve 33 corresponding to {TAIL ~ the degree} of reductive operation, the operational mode of the PSA apparatus 11 is changed corresponding to {HEAD ~ the reduced flow rate} 
As described above , in the procedures of switching to a reductive operation , after the flow rate of the product gas is reduced by the flow control valve 33 corresponding to { TAIL ~ the degree } of reductive operation , the operational mode of the PSA apparatus 11 is changed corresponding to { HEAD ~ the reduced flow rate }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD