API 682 Mechanical Seal Flush & Heat Calculator
Calculate mechanical seal face frictional heat generation, minimum required flush flow rate (GPM), and temperature rise per API 682 / ISO 21049 standards.
Pump Shaft & Seal Chamber Operating Conditions
Flush Fluid & Thermal Limits
API 682 Sizing Results
Recommended Tools & Equipment
Tested hardware and components for high reliability
Frequently Asked Questions
Why does a mechanical seal require flush flow?
Mechanical seal faces operate with an ultra-thin microscopic fluid film (0.5 to 1.5 microns). Friction generated at high rubbing velocities generates heat that can boil the fluid film. Flush flow removes this frictional heat, sweeps debris away, and maintains fluid film stability.
What is the standard allowable temperature rise (ΔT) across seal faces?
Per API 682, the flush flow must limit the temperature rise through the seal chamber to between 10°F and 15°F (5.5°C to 8.3°C). This ensures the fluid in the seal chamber remains at least 20°F (11°C) below its atmospheric boiling point or vapor pressure curve.
What is the difference between API Plan 11 and Plan 23?
Plan 11 routes fluid from pump discharge through an orifice directly into the seal chamber and back into the pump suction (open circuit). Plan 23 uses an internal pumping ring to circulate seal chamber fluid through a dedicated heat exchanger and back, making it dramatically more energy-efficient for hot services like boiler feed.