| abstract |
A blending apparatus for continuously and accurately blending a plurality of diverse, normally gaseous or volatile liquid components, preferably two or three, at low pressures. In a preferred embodiment, the apparatus blends a first stream of volatile liquid component, preferably carbon dioxide with a liquid stream of any suitable hydrocarbon (including halogenated hydrocarbons) blowing agent in accordance with any predetermined ratio desired by those skilled in the art before introducing the blend into a suitable extrusion process for preparation of polymeric foams and the like. The apparatus combines the liquid components at a pressure substantially lower than the elevated pressure required during the extrusion process. In an alternative embodiment, the blending apparatus blends a liquid stream of volatile liquid component, preferably carbon dioxide with a liquid stream of a first hydrocarbon blowing agent in accordance with any predetermined ratio and subsequently blends a second hydrocarbon blowing agent with the blend of the liquid carbon dioxide and the first hydrocarbon blowing agent. |