#mechanicalsealsystem

What is API Plan 21?

API Plan 21 is a cooled recirculation flush plan defined by API 682-. It is specifically engineered for high-temperature process services where the hot fluid cannot sustain stable seal operation without supplementary cooling.

How Does API Plan 21 Work?

The system draws process fluid from the pump discharge, routes it through a restriction orifice for flow limitation, and then through an API 682 Plan 21 heat exchanger-. This reduces the fluid temperature before delivering the cooled flush fluid into the mechanical seal chamber.

Why Choose API Plan 21?

As a cooled derivative of Plan 11, its primary duty is cooling the flush fluid and stabilizing the mechanical seal end faces-. This function:

Suppresses process fluid vaporization

Reduces coking formation at elevated temperatures

Maintains intact lubricating liquid film between mating seal faces

These are necessary conditions to achieve low-leakage, long-term reliable seal service.

Custom Solutions from Dandong Runhe Seal Co.,Ltd.

We provide custom seal support system solutions- with properly sized Plan 21 heat exchangers for various high-temperature pumping services. As a professional mechanical seal manufacturer, we can design the right system for your specific needs.