Experimental Study of the Effects of a Low-expansion Foam Generator Structure on the Foaming Quality

Aqueous film-forming foam is used widely as a means of fire extinguishing, especially for both chemical process industry and oil industry fires. The corresponding low-expansion foam generator always uses negative pressure generated by a high-velocity jet to draw in air to create a low-expansion foam. Considering the interactions between factors, an orthogonal test was established to characterize their performance. This conclusion was verified using the method recommended in GB15308-2006, the standard issued by the Standardization Administration of the People's Republic of China. It was found that the nozzle convergence angle and the ratio of the nozzle position to the throat pipe diameter of the generator were the predominant factors. The optimal foam generator configuration had a nozzle position of 1.2 times the diameter of the throat pipe, a nozzle convergence angle of 11º and throat pipe length of 7.5 times the diameter of the throat pipe. This study contributes to the optimization of a low-expansion foam generator.