Patent GB-1373671-A (GB)
Title: Centrifuge for treating liquid
IPC: B04B5/04
Filed: 1972-03-10
Abstract: 1373671 Centrifugal separator AGA AB 10 March 1972 [15 March 1971] 11304/72 Heading B2P A centrifuge for treating liquid by separating it into fractions of different densities, and/or for washing solid particles, e.g. blood cells, suspended in the liquid, comprises a rotor 11; a plurality of collapsible closed containers 16, 17 which are disposed in the rotor for rotation therewith and which are interconnected by means of a collapsible conduit 26 (30) for passing liquid between the containers, a first one (17) of the containers being adapted to initially hold a discrete quantity of a liquid to be treated and a second one (16) of the containers being adapted to receive a low density liquid fraction from the first container and/or to initially hold a discrete quantity of treating solution; and a peristaltic pump 32 mounted on the rotor for rotation therewith and acting on the flexible conduit 26 (30) to selectively move liquid through the conduit and prevent liquid flow through the conduit. The rotor 11 includes a bowl 13 which is journalled in a bearing 15 and is driven via belting by means of a motor 12. The containers are made of flexible sheet material, e.g. a laminate of polyethylene and polyester. The lower container 16 is made of three circular sheets 18, 19, 20 which define between them compartments 23, 24 and the collapsible conduits 26, 30. The compartment 23, when treating blood, initially holds wash solution and compartment 24 is initially empty. The conduit 26 serves for the flow of wash solution from compartment 23 to a connecting tube 27 secured to the upper sheet 20. The upper compartment 17 consists of sheets 33, 34 joined to define between them an annular compartment which initially holds a quantity of blood cells suspended in a liquid preservative and which communicates with the tube 27 via a collapsible conduit 38 and a tube 37. A filler ring 40 and a backing plate 41 are disposed between the containers 16 and 17. A clamping mechanism, 45, 46, 47 cooperates with a cover plate 42 and the bowl 13 to hold down an annular body 44 made of soft rubber mixed with lead granules against the containers. A photoelectric detector 48 signals the presence of red blood cells in tube 37. The pump 32 comprises two concentric and independently movable circular groups of rollers 49 and 52 which respectively engage conduits 26 and 30 through a flexible diaphragm 55 to compress these conduits against backing plate 41. Rotor members 50 and 53 on which the rollers 49 and 52 are respectively mounted are normally stationary with respect to the centrifuge rotor 11 but can be slowly rotated with respect thereto. Clockwise rotation of rotor member 53 is derived from the journal member 14 of the bowl 13 through gears 56, 57 and a clutch 58 and anti-clockwise rotation of rotor member 53 through gears 59, 60 and a clutch 61. For treating blood cells in container 17, the centrifuge rotor 11 is caused to rotate with clutches 58, 61 disengaged so that pump rotor members 50, 53 rotate in unison with the rotor 11 owing to the friction between the rollers 49, 52 and diaphragm 55. Under the influence of centrifugal force the heavy soft rubber of body 44 is forced outwardly to apply an external pressure to containers 16, 17 which forces the liquid therein inwardly causing conduits 26, 30 to expand. But since the rollers 49, 52 are stationary with respect to rotor 11 and containers 16, 17 and compress the conduits 26, 30 no liquid is permitted to pass through the latter. The red blood cells accumulate in the radially outer portion of container 17 while the lighter preservative liquid is collected radially inwardly. Clutch 61 is then engaged to cause anti-clockwise rotation of rotor member 53 and pumping of the preservative liquid from container 17 into compartment 24 of container 16 through conduit 38, tubes 37, 27 and conduit 30. Since rotor member 50 is still stationary, with respect to rotor 11, the preservative liquid is prevented from flowing through conduit 26. Where detector 48 signals the presence of red blood cells in tube 37, clutch 61 is -again disengaged and clutch 58 engaged to cause clockwise rotation of rotor member 50 and pumping of wash solution from compartment 23 into container 17 through conduit 26, tubes 27, 37 and conduit 38 while rotor member 53 is held stationary to prevent flow through conduit 30. When sufficient wash solution has been transferred, clutch 58 is disengaged so that both conduits 26, 30 are closed whereupon rotor 11 is rapidly braked to low speed to agitate and thoroughly mix the wash solution and blood cells. The wash solution is then separated from the blood cells and transferred to compartment 24 of container 16 in the same manner as the preservative liquid. The washing step may be repeated many times.