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Volume Measurement
The volume is displayed in ml.
In the test phase, the current diffusion value is displayed as a graph and additionally
as a numerical value. The graph is designed so that the limit is drawn as a red line.
If the actual value is below this, the integrity of the filter is proven.
7.5 Bubble Point Test
In wetted membranes, the wetting liquid is held inside the porous structure by
capillary force. This force increases as the pore size decreases. A specific gas pressure
dependent on the pore size of the membrane is necessary to force out the liquid
from the pores. This pressure is generally designated as the “Bubble Point,” or
B.P. for short. It generally indicates the largest pores of a filter since liquid is first
expelled from them. Hence, it follows that the B.P. of a filter depends both on the
filter material (the contact angle varies from material to material) and, in particular,
on the surface tension of the wetting fluid. Low surface tensions, as are present
in organic solvents, detergents and emulsifiers yield low B.P.’s.
Since the surface tension also depends on the temperature, different wetting fluid
temperatures will also yield different B.P.’s. The Bubble Point Test is especially
suitable for checking the integrity of disc filter systems. (For a more detailed
description, see Chapter 12, Appendix).
Test parameters: Bubble Point Test
Enter the parameters: BP Min. in mbar
BP Max. in mbar
System test code: e.g. standard
Net volume: Enter or measure, if Enter: Volume in ml
Fig. 7-16 | Volume Measurement
Fig. 7-17 | Test Phase
Fig. 7-18 | Test parameters:
Bubble Point Test
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