| abstract |
A low-boiling foaming agent such as dichlorodifluoromethane is added to one of the reactive liquids of a system for forming a foam such as polyurethane foam, by pumping the reactive components and the foaming agent to elevated pressure in three separate pumps that are mechanically linked so as to maintain a fixed delivery ratio to each other, then mixing the foaming agent with one of the liquids, and finally mixing that latter mixture with the other reactive liquid and ejecting a single stream of material that foams on a substrate and then cures. |