Plan 23 - Single seals - Closed loop circulation through a heat exchanger
Description: Plan 23 is a closed loop system using a pumping ring to circulate product through a heat exchanger and back to the seal chamber.
Advantages: More efficient than a Plan 21 and less chance of heat exchanger fouling. Reduced temperature improves lubricity and improves vapor pressure margin.
General: Preferred plan for hot applications. Close clearance throat bushing is recommended to reduce mixing of hot product with cooler closed loop system fluid.