Ceramic filter, fiber membrane pore throat diameter bubble pressure test technology - Database & Sql Blog Articles

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The basic principle of bubble pressure method:

Taking a certain membrane material as an example, the membrane is sufficiently wetted with a liquid that can be infiltrated with it, and the infiltrating liquid will be

Tightening in the pores of the membrane; applying a gradually increasing gas pressure to one side of the membrane, and when the gas pressure reaches a pressure greater than the surface tension of the infiltrating fluid in a certain pore size, the infiltrating liquid in the pore size will be pushed out by the gas; The smaller the pore size, the higher the pressure generated by the surface tension, so the higher the pressure of the gas to be applied to the immersion liquid is. The same, it can be seen that the immersion liquid in the pore with the largest pore diameter will be first pushed out to make the gas permeable. Then, as the pressure increases, the pore size increases from large to small, and the immersion liquid in the pores is sequentially pushed out to allow the gas to pass through until all the pores are opened to achieve the same transmittance as the dry film;

The pressure corresponding to the first opened hole is the bubble point pressure, and the aperture corresponding to the pressure is the maximum aperture;

during this process,

Record pressure and flow in real time

,

Get pressure

- flow curve;

Information on the size of the pressure reaction pore size, information on how much the flow responds to a certain pore size;

Then test the dry film

of

pressure

-flow

The curve can be calculated according to the corresponding formula

The maximum pore size, average pore size, minimum pore size, and

Pore ​​size distribution

,

Transmittance.

The relationship between pore size and pressure is like the Washburn formula:

D=4γCos θ/ p

In the formula, D = pore diameter γ = surface tension of liquid θ = contact angle and p = pressure difference

Percentage of flow by pore size distribution:

f(D) = - d[Fw/Fd)x100]/dD

In the formula, Fw is the wet sample flow rate, and Fd is the dry sample flow rate.