Icing preventor

Claim 1

Apparatus for connection to an outdoor water line carrying water at a selected pressure, for producing a selected low flow rate of water from said water line, when the outdoor temperature drops below a selected temperature, comprising: (a) a single orifice of selected small diameter in the end of said water line; (b) body means comprising a closed chamber and a housing for a valve closure means, said closed chamber means having an expansible portion, said chamber means filled with a selected condensible gas for which the vapor pressure varies with temperature in a known manner; (c) said closure means being positioned adjacent said single orifice, a portion of said closure means extending beyond and exteriorly of the housing in all positions of said closure means; (d) means connecting said expansible portion of said chamber means to said closure means; (e) said means connecting said expansible portion of said chamber to said closure means including series compliant means; and (f) helical spring means being positioned between said closure means and said orifice, said helical spring means surrounding said orifice and said exterior portion of said closure means; whereby when the outdoor temperature is above a selected value, said expansible portion will move outwardly to press said exterior portion of said closure means against said orifice, to close off said flow; and when the outdoor temperature is below said selected value said expansible portion will move inwardly away from said exterior portion of said closure means permitting water flow through said orifice.