The pressures of foams in a leading pipe of the foam washing apparatus (inner foam pressure) were measured with changing the opening of mesh screen and air flow rate, and the mechanism of foaming action at the opening of mesh screen in the vertical fixed type of foam washing was predicted. Moreover, the effect of foaming action on the detergency of palmitic acid adhered on the mesh screen was studied, and following results were obtained.
1) The inner foam pressure is divided into two elements, one of which is capillary pressure P
1 required to the foaming action, and the other is P2 proportional to the air flow rate.
2) P
1 suggested that the foaming action occurred when the contact angle of foam film to the face of mesh screen grew to 30°. This P
1 is correlative to the force of bubbling sorption involved in a unit foaming action, and P
2 to the frequency of that action.
3) With decreasing the opening of mesh screen, or with increasing the air flow rate, the inner foam pressure increased and the detergency also increased. Accordingly, we can realize that the foaming action from inner part of substrate increased the detergency.
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