| 摘要 |
An enclosed vessel for containing a supply of hardenable liquid to be dispensed together with selectively operable pressurizing means for introducing air into the container to exert a superatmospheric pressure on the surface of said liquid, whereby to discharge such liquid from the container into the atmosphere through a discharge line controlled by a dispensing valve and having an intake end submerged within the liquid. There are provided evacuating means operable during discontinuance of the pressurizing operation to evacuate air from the container whereby to withdraw liquid from the discharge line back into the vessel and, optionally, to maintain a reverse flow of air through the discharge line so that the air is introduced into the liquid at a submerged location to thence bubble upwardly through the liquid. In a modified version, the pressurizing air also is introduced into the vessel at a location beneath the surface of the liquid so that it, too, bubbles up through the liquid.
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