SE365426

1,238,147. Stirrers; filter for analysis. BECKMAN INSTRUMENTS, Inc. 5 June, 1970 [30 June, 1969], No. 27166/70. Headings B1C and B1D. A combined stirrer and filter for use in a test-tube or similar container comprises a body 6 having ramp surfaces as at 8, 10 separated by a. partition 12 to which is attached a screen 26. There are vertical slots 18 (and 20, Figs. 2-4 not shown) in the body, which rests on a flat surface 16 or on a spike attached thereto. When the device is rotated clockwise as seen from above, the ramp surfaces cause fluid to flow upwards from their upper ends and through the screen, and to circulate downwards again through the screen in the region of the slots 18, (20). The screen may be cut away in the region of the downward flow so that foreign matter is retained only on its underside. The stirrer is rotated by the action of an external rotating field on the permanent magnet 24 which is received by the void 22. The body 6 may be of plastics and the screen a plastics mesh of 30-40 strands/inch.