此款求積儀由美國Builders Iron工廠製造，其基本原理類似極座標式求積儀，可用來量測文氏流量計(Venturi Meter)的流速表，以得到流體流量。

This planimeter was manufactured by Builders Iron Co. in the USA. Its working principle is similar to that of a polar planimeter and can be used to measure the flow velocity of a Venturi meter to determine fluid flow rate.