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. John Marshall was born on September 24, 1755 at Germantown (now Midland) in what became Fauquier County, Virginia four years later. He served first as lieutenant, and after July, 1778, as captain in the Continental Army in the Revolutionary War. John Marshall spent the winter of 1777-1778 with the troops in Valley Forge. In 1781, he resigned his military commission and studied law. He soon began practicing in Fauquier County and later in Richmond.