Abstract: A ventilator adapted to project a uniform air curtain of high velocity and of high pressure. The ventilator is in the form of an elongated air pump in which a rotor shaft is mounted eccentrically within an open coil helix lining the tubular casing of a stator assembly having parallel intake and outlet slots extending the full length of the casing. The shaft is provided with centrifugal vanes which are caused by centrifugal force to engage the convolution of the helix and to slide therealong, whereby the helix functions to engage the vanes without interfering with the flow of air into the pump and its ejection through the outlet.