Integral Pumping Devices for Dual Mechanical Seals: Hydraulic Performance Generalization Using Dimensional Analysis

An experimental study is carried out investigating hydraulic performance for various designs of dual-mechanical-seal cartridges with integral pumping-rings. The tested devices are classified into two main families: radial-flow and axial-flow. The radial-flow family utilizes the modified-paddle-wheel (MPW) pumping ring with either a radial or a tangential oriented cartridge outlet port, while the axial-flow family utilizes the pumping scroll (PS) pumping ring in the following cartridge-geometries: single-pumping-scroll (SS) and double-pumping-scroll (DS); as both types can be of either a radial or a tangential outlet port; and of an internal clearance value complying with American Petroleum Institute (API) 682 standard or smaller clearance. An experimental setup is constructed, and appropriate instrumentation is employed to measure inlet pressure, outlet pressure, rotational speed, and barrier fluid flow rate acquiring flow-head characteristic curves. Moreover, empirical generalized characteristic curves are deduced from experimental observations obtained from the present study and previous companion work. The generalized curves can be employed in estimating pumping ring performance for a different size or other operation conditions such as varying rotational speed or fluid type. They can be also utilized to validate numerical simulations for geometrically similar designs.