Over the Top Foam Generators (OFG) are air aspirated discharge devices that delivers foam solution into the surface of flammable liquid. They are installed on the outside wall of storage tanks above the level of stored product. They produce and inject foam solution into the liquid surface. Foam Generators can produce foam with expansion ratios of up to 4:1 depending on foam concentrate type and capacity requirements. The OFG is connected to a foam solution supply system and equipped with a test outlet, that makes it possible, by simply moving a test cover to test the unit without putting foam into the tank.