Double-ended blower and volutes therefor

A CPAP/NIPPV apparatus for treatment of a patient with a sleeping disorder, the apparatus including a blower for supplying breathable gas to the patient, comprising:

• a casing;
• a gas flow path between a gas inlet and a gas outlet of said casing;
• a motor located within said casing;
• a motor drive shaft including a first shaft end and a second shaft end defining a rotational axis, said first and second shaft ends extending from opposite sides of the motor;
• a first impeller within a first volute and secured to the first shaft end, said first impeller including a first gas intake, said gas inlet axially aligned along said rotational axis with the first impeller;
• and
• a second impeller within a second volute and secured to the second shaft end, said second impeller including a second gas intake, said first and second impellers being disposed axially between said gas inlet and said gas outlet to cooperatively pressurize gas flowing from said gas inlet to said gas outlet, wherein said first and second gas intakes are coaxial with said motor drive shaft, and wherein the gas flow path includes a length of piping outside said casing connecting said first and second volutes.