The invention relates to a micro-blower used for a medical ventilator and a method for assembling the same. The micro-blower comprises an electric motor having a rotary shaft bearing a vane wheel, said electric motor being contained in a peripheral cowling, said vane wheel being arranged between a lower volute and an upper volute, the lower volute comprising a central passage encircling the peripheral surface of the cowling. The cowling of the motor comprises an upper peripheral lip that projects radially away from the external peripheral surface of the cowling. The central passage of the lower volute is bordered internally by an annular shoulder, an annular seal being arranged on said annular shoulder. The lower volute also comprises a number of internal stops that are borne by the internal surface of the lower volute . The upper peripheral lip of the cowling of the motor is positioned between the annular seal and the internal stops of the lower volute, said internal stops bearing against said upper peripheral lip of the cowling of the motor so as to achieve compression of the annular seal between said upper peripheral lip of the cowling and the annular shoulder of the lower volute.
