White porcelain Buchner funnel with a perforated fixed plate, in six sizes from 70 mm to 240 mm to match 7 cm through 24 cm filter papers.
F3270
F3271
F3272
F3274
F3254
F3276
A Buchner funnel separates a solid from its liquid under vacuum instead of gravity. The flat perforated plate supports a filter paper across its whole area, so suction pulls the liquid through evenly and the filter cake builds as a uniform layer that can be washed and lifted out intact.
These are white glazed porcelain, one piece with the plate fired in. Porcelain is the material of choice here for reasons a plastic funnel cannot match: it takes hot filtrates and strong acids without softening or crazing, it will not deform under vacuum, and it can be dried in an oven with the cake still in place — routine in gravimetric work where the cake is weighed after drying.
Size is chosen by filter paper, not by the volume being filtered:
| Catalog | Funnel | Filter paper |
|---|---|---|
| F3270 | #2, 70 mm | 7 cm |
| F3271 | #2A, 90 mm | 9 cm |
| F3272 | #3, 110 mm | 11 cm |
| F3274 | #4a, 150 mm | 15 cm |
| F3254 | 240 mm | 24 cm |
| F3276 | #6, 240 mm | 24 cm |
The paper must lie flat and cover every perforation without curling up the wall. A paper that is too small lets liquid bypass the filter through an uncovered hole; one that is too large curls at the edge and channels. Match the pair exactly.
Use with a filter flask and a vacuum source, seating the funnel on a rubber adapter. These sizes are equivalent to the Coors 60243 through 60248 range.