With a pressure vacuum breaker, however, a drop in the pressure of the water enables the spring to snap the check valve shut. As soon as the water pressure drops, the check valve closes and backflow does not occur.n a pressure vacuum breaker, the water travels through a check valve and causes a poppet to raise up a guide into an air inlet. The air inlet also has a valve which ordinarily remains closed.
Peter Marshall was born Ralph Pierre LaCock on March 30, 1926, to Ralph and Jean LaCock, a show business family, in Huntington, West Virginia. Following his father's death when Marshall was a teenager, he moved to New York City to be with his mother, a costume designer.
John MARSHALL, paternal ancestor of Alfred MARSHALL, was born in Derbyshire, England, and migrated from Elton parish m that shire in 1686 to America, and after locating for about a year in Blockley township, Philadelphia county, located in Darby, Delaware county.