Abstract: Abstract: The ring pump type B foam mixing device is a system used to mix the foam solution and the aqueous solution according to a certain standard. Aiming at the shortcomings of the traditional device, such as low mixing accuracy, poor stability and needing manual control, the foam tank fire truck was taken as the research object, in accordance with the requirements of GB 7956.3-2014, Fire fighting vehicles-Part 3:Foam fire fighting vehicle, a mathematical model of foam and water mixing ratio control was established. PID and Smith-PID predictive control algorithms were applied to follow-up control the foam and water flow ratio in the model, and the foam ratio mixing control system hardware and software were developed. A set of ring pump type B foam mixing device and experimental program was designed and developed, and the experimental results were analyzed to achieve a stable and accurate output of 3% or 6% foam solution to meet the requirements of firefighting.

Key words: Key words: type B foam mixing device, fire piping, flow control, PID control, Smith-PID predictive control