The Select and Use of Filter Paper
Select of Hawach Filter Paper
These should be the major points to consider before selecting the filter paper:
1. Larger effective filter area means larger usable filter area, larger dust holding capacity, lower resistance, longer service life, and more cost.
2. Shorter fiber diameter means better blocking probability and higher filter efficiency.
3. Higher adhesive content in filter medium means stronger tensile strength, higher filter efficiency, less desquamation of fibrilla, less dirt retention but higher resistance.
Use of Filter Paper
1. Fold the filter paper in two for twice to make it in a shape of 90° central angle.
2. Open the folded filter paper into a funnel which has three layers on one side and one layer on the other side.
3. Put the filter paper into the funnel with the former edge lower than the latter edge. Add some clear water on the side of the funnel to make the wet filter paper cling to the funnel’s inner wall.
4. Put the funnel on the funnel stand and lay a beaker or a test tube under the funnel stem to hold the filtering medium.
5. Pour the liquid that needs to be filtered into the funnel with the beaker and glass rod. Make sure that the liquid level is lower than the filter paper.
6. When the liquid flows down the funnel stem, pay attention that if the liquid is flowing down the beaker’s wall afterward. Otherwise, you should move the beaker or rotate the funnel.