A small
oxygen enriching apparatus which can supply
oxygen-enriched gas at high flow rate without imparting unnatural
sensation to a user, as well as a controller and recording medium therefore. In step 100, a judgment is made as to whether a flow rate set by use of a flow-rate setting unit 45 is equal to or less than a continuous base flow rate (3 liters / min). When the set flow rate is a low flow rate of not greater than 3 liters / min, breath-synchronized operation is not performed (continuous supply is to be performed), and therefore, in step 110,
oxygen-enriched gas is supplied continuously at the set flow rate. When the set flow rate is a high flow rate of greater than 3 liters / min, breath-synchronized operation is to be performed, and therefore, in step 120, the orifice is set to an opening that enables supply at 5 liters / min. In step 140, in order to perform breath-synchronized operation, control for opening and closing an
electromagnetic valve 47 is performed. Through this operation, the oxygen-enriched gas is supplied at a high flow rate (5 liters / min) in the
inhalation period of each
breathing cycle and at a low flow rate (2 liters / min) in the
exhalation period via a bypass flow passage 50.