Diverter Valve
Diverter valve is used to prevent backfire in exhaust system during sudden deceleration. Valve senses sudden increases in intake manifold vacuum causing valve to open, and divert air away from exhaust system. This allows air from air pump to pass, through valve and silencer, to atmosphere.
A pressure relief valve controls system pressure by diverting excess pump outlet air (developed at higher engine speeds) to atmosphere through silencer.