Surface active materials tend to stabilize foams by lowering the interfacial tension between water and air. Sometimes these factors can be minimized. These involve application of vacuum and some type of fluid motion to separate dissolved and entrained air from the water phase.Ī long-term answer to air problems in a paper mill also should include consideration of chemical factors that tend to stabilize foams. Many modern paper machines, especially those producing fine and specialty paper grades, contain deaerating equipment. It is important also to make sure that the showers within air-padded headboxes are working effectively. Often the breakage of surface foam is promoted by spray showers. On a basic, traditional paper machine the main mechanism of air release is the coalescence, creaming, and breakage of bubbles in the white water tray and white water silo areas, just after the paper has been formed. Also it is important to realize that the paper machine environment contains all of the key elements needed to create foam - water, air, lots of agitation and splashing, and various substances that can act as stabilizers. Leaky seals on pumps are a leading cause of unnecessary air entrainment. Though our main concern in this website is in regards to chemical factors, it is important to consider mechanical factors that can be contributing to air problems.
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