| 摘要 |
An apparatus for spraying plastic foam includes two containers respectively adapted to hold a solution of a urea-formaldehyde precondensate in a first aqueous medium and a second aqueous medium including a catalyst which causes rapid hardening of the precondensate when the two aqueous media are mixed. A foaming chamber communicates with a source of compressed air and with one of the containers for dispersing the gas in the corresponding medium and for thereby forming a foam. A first conduit connects the foaming chamber to a mixing chamber, and a second conduit connects the other container to the mixing chamber. A third conduit leads outward of the mixing chamber and terminates in a nozzle orifice normally open to the atmosphere. The compressed air is used for conveying the foam and the medium in the other container to the mixing chamber for continuously mixing the contents of the mixing chamber and for conveying the resulting mixture outward through the nozzle orifice when the latter is open. When the orifice is blocked, a check valve in the first conduit prevents flow of the catalyzed mixture into the foaming chamber.
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