Patent GB-1505057-A (GB)
Title: Centrifuge
IPC: B04B5/04
Filed: 1976-09-24
Abstract: 1505057 Centrifugal separator BECTON DICKINSON & CO 24 Sept 1976 39651/76 Heading B2P A centrifuge comprises a stator 21, Fig. 1, formed with a chamber 26 in which a rotor 22 is rotatably mounted and is connected to variable drive means 30 on the stator; a cover 25 on the stator shiftable between open and closed positions; a variety of sample holding means 56, 65, Figs. 2 and 5, on the rotor for holding a number of different types of sample holders, one of which is shown at 58 in Fig. 2; control means 29 connected to the drive means to vary the speed of the rotor to correspond to the speed required for centrifuging the samples being held in the particular sample holders and for starting and stopping the centrifuge; the rotor including a disc-shaped head 45 having surfaces and openings 64, Fig. 5, for receiving the sample holding means 56 and 65 respectively; a member 69, Figs. 1 and 3, including extendable flexible flaps, mounted on the underside 53 of the rotor head 45, the flaps, when sample holders are not present in the openings 64 and when the rotor is rotated at high speed, being extended by centrifugal force opposite the openings to close the latter and prevent air flow therethrough to reduce windage power losses, and, when sample holders are received in the openings and when the rotor is rotated at low speed, being engaged by the sample holders, Fig. 7, to expose the openings to air flow. The bottom half 24 of the stator is bowl-shaped with three legs 27 extending downwardly. A peripheral skirt 28 encompasses the legs 27, the control means 29 and the motor 30. Resilient supporting feet 39 and 40 extend respectively from skirt 28 and from two of the legs 27 to minimize rotor vibration and noise. The legs have also anti-vibration resilient bases 41 which support a plate 36 on which the motor 30 is mounted. The motor is sealed to the stator by a resilient, annular, anti-vibration bumper 47. Cooling air drawn through the motor into the chamber 26 leaves the latter through apertures 49, 50. The rotor head 45, which may be formed of extruded aluminium, has eight sample stations of which the stations 51 are designed for hematocrit determinations and stations 52 for handling tubes of blood or urine samples. At each hematocrit station a T-shaped plate 56 is fastened to the upper surface 54 of the rotor head and has three slots in which hematocrit tubes 58 are accommodated in slanting fashion. A scale 56a located on the plate 56 permits direct reading of the results after centrifugation. Each station 52 includes an opening 64 in the rotor head 45, Fig. 5 for receiving a trunnion assembly 65 having wells 66 in which tubes containing blood or urine samples are accommodated, the assembly having trunnions 67 which are seated against tapered shoulders 68, Fig. 7, on the rotor so that during centrifugation the assembly is swung freely with the tubes passing from a vertical to an outwardly downwardly inclined position. The member 69 of rubber or nylon fabric is of cruciform shape, Fig. 3, to define the flaps and is retained on the underside 53 of the rotor by a plate 50'. The cover 25 for the stator, Fig. 1, is pivotable at one end about a pin 72 and has at its other end a pivotable and spring biassed latch member 74 which is engageable with a locking prong 78 on the stator. A switch 83 forming part of the control means 29 can only be activated to start the motor 30 by a spring-loaded control rod 82 which is pushed downwards when the cover is closed.