Abstract: An air lock for injecting a fibrous or granular material, such as insulation, into an airstream. The air lock has two counter-rotating, generally cylindrical rollers in facing contact with each other along their edges, made of a resilient material such as a closed cell foam. The rollers are also in facing contact with the outside of a tube or cylinder through which the airstream flows. The insulation is positioned on top of the rollers, and the rollers feed the insulation between them and into the airstream. The contact between the rollers and between the rollers and the injection tube create the air lock between the airstream and the atmosphere. The invention can also be used in a vacuum machine, particularly suited for vacuuming and collecting fibrous or granular materials.