دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a reciprocal pumping unit in which one or more power cylinders are placed over the wellhead and a counterbalance system using compressed air or gas is provided. On the upstroke, high-pressure gas is applied to the underside of the pistons of the inside power cylinders, and low-pressure gas above the pistons is exhausted to the sales line. On the downstroke, high-pressure gas is applied to the top of the pistons, and the low-pressure gas below the pistons is exhausted to the sales line.