SSI model semi sub surface foam injection systems are used together with HBG units, to deliver expanded foam over the stored liquid level from inside the storage tank. Inside the unit a special synthetic hose contained with a determined length according to vessel height retracts by using pressure and flow of the expanded foam applied to the unit. A foam blanket created by expanded foam extinguishes fire by covering the entire liquid surface. Usually, SSIs are equipped with a rupture disc to seal the container from the static pressure created by the height of the liquid stored in the tank.
Rupture discs can be made of stainless steel or other materials on request. Carbon Steel and Stainless-Steel materials are available on request.