Patent ID: 8650694

Claim:
A pipeline pig comprising: a longitudinal pig body having a single bypass flow passageway, and a plurality of external circumferential sealing elements, said bypass flow passageway having a venturi located toward a rearward end of the longitudinal pig body; and a modulating valve located within said single bypass flow passageway and between an inlet side and an outlet side of said venturi; said modulating valve having a first position and a second position, said first position allowing a predetermined maximum bypass flow past said modulating valve, said second position allowing a predetermined minimum bypass flow past said modulating valve, wherein the predetermined maximum and minimum bypass flows flow in a same direction as the main product flow propelling said pipeline pig forward under differential fluid pressure when in a pipeline; whereby said modulating valve moves to said second position substantially instantaneously upon said pipeline pig stalling and from said second position toward said first position substantially instantaneously upon said pipeline pig accelerating.