| 摘要 |
The pipe bleeder includes a small holding tank and a sample tube, both of which are filled with water and exposed to the ambient atmospheric temperature. The water in the sample tube freezes first when the ambient temperature is at freezing, which in turn causes a piston and then a push rod in the sample tube to move, the top of the push rod acting against a small cover plate in the holding tank, moving it away from a drain connection. When the cover plate is so moved, water from the water supply pipe will flow at a relatively slow but steady rate through the drain connection to the environment, maintaining a flow of water through the supply pipe and thus preventing the water in the water supply pipe upstream of the pipe bleeder from freezing. An exterior thaw tube is also attached to the drain connection in the holding tank. When the ambient temperature increases to a few degrees above freezing, the ice in the thaw tube will thaw, resulting in a spray of water from the end of the thaw tube, which is directed into an interior thaw tube which is inside the sample tube, thawing the ice in the sample tube. The thawing of the ice in the sample tube results in the piston and the push rod retracting and the cover plate moving back into place, closing off the drain opening.
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