1. Add before foaming: This method can suppress the foam by adding anti-foaming agent beforehand in the system that may produce foam. For closed containers and devices, defoamers are effective at eliminating foam.

2. Continuous instillation addition: When the foaming liquid is either circulating or flowing, the defoaming agent will be consumed along with the circulating flow of the foaming liquid. In this case, the continuous defoaming agent is added dropwise. The method, the defoamer can effectively play the role of eliminating foam, if supplemented by a metering pump can effectively control the amount of added, to achieve the most economical use of defoamer.