| 摘要 |
Apparatus for connection to an outdoor water line carrying water at a selected pressure, for producing a selected low flow rate of water from the water line when the outdoor temperature drops below a selected temperature, which comprises an orifice in the end of the water line of selected small diameter, a closed chamber means having an expansible portion, filled with a selected condensible gas, for which the vapor pressure varies with temperature in a known manner, and closure means positioned adjacent the orifice and means connecting the expansible portion of the chamber to the closure means to shut off the flow of water when the temperature is above a selected value, and to open the orifice to a small trickle flow of water, whenever the temperature outdoors is less than a selected value, such as the freezing point of water.
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