GB1159868A - Air Driven Centrifuge - Google Patents

Abstract

1,159,868. Centrifugal separators. G. N. HEIN. 22 Sept., 1967. No. 43329/67. Heading B2P. In an air-driven centrifuge for separating a liquid mixture, e.g. blood, into fractions of different densities and comprising a rotor 20 which when stationary, Fig. 1, rests with a portion of its lower surface against a pad 37 on a stator 40, compressed air introduced through a tubular connector 61 and a chamber 49 in the stator is fed, by means of upwardly and angularly directed air jet holes 52, between the pad 37 and the lower surface of the rotor 20 to cause the latter to rotate and to be supported on an air cushion out of engagement with the pad 37 while rotating, Fig. 2, the liquid mixture being received in the rotor through an opening 85 in a receptacle 80 which has a flexible bottom portion 81 adapted, during rotation of the rotor, to be flexed by liquid introduced into the cavity 21 of the rotor so as to move at least one fraction of the liquid mixture inwardly and out through the opening 85 into a collector 70. The undersurface of the rotor 20 is formed with flutes 23 to facilitate driving by the air discharging from the holes 52. The receptacle 80 has a transparent rigid upper portion 82. The pad 37 has two downwardly extruded portions 38 which rest on a shoulder 36 formed in the stator and which allow rocking and precessional movement of the pad which acts as a buffer for vibrations resulting from rotation of the rotor at slow speeds during starting and stopping. The liquid, e.g. sucrose solution, to be introduced into the cavity 21 of the rotor is contained in a reservoir 60 attached to the stator. The liquid is pumped via flexible hoses 62, 63 through a bore 66 in a plug 55, 57 which is threaded into a core portion 50 of the stator and which has a tube 67 extending from its top into a bore 24 of the rotor. The bore 24 communicates with passages 25 which open into the rotor cavity 21, the openings of the passages being covered by a washer 29 which prevents the receptacle 80 from entering the openings during rotation of the rotor but which is displaced upwardly, Fig. 2 when the liquid is introduced into the cavity. Delivery of the liquid is regulated by altering the gap between the rotor and the end of tube 67 by screwing or unscrewing the plug 55, 57 which is outwardly biased by a spring 64 to prevent it from turning as a result of vibrations. When the rotor is stoped liquid drains back from the cavity 21 into the passages 25, which it enters through grooves (not shown) on the underside of the washer 29, and flows through an annular passage 58 and openings 59 into the reservoir 60. An air vent 26 is provided in the rotor. In a modification, the reservoir 60 is not in coaxial alignment with the stator and rotor and the plug 55, 57, which in this case lies outside the reservoir, can be manipulated while the centrifuge is operating. In a further modification, Fig. 6, a disposable plastics rotor has rigid bottom and top portions 81", 82". A flexible membrane 78 inside the rotor forms a receptacle with the top portion 82". Flutes 23" are moulded in the bottom portion 81".