Water Flow Rate Calculator (GPM)
Why does the hot water line option lower the velocity limit?
Hot copper supply lines are limited to about 5 ft/s to prevent erosion-corrosion (pinholing) of the tube wall, per ASTM B88 and ASPE guidance. Checking Hot water line overrides the material general ceiling with this 5 ft/s cap, which sustained over-velocity in hot copper can otherwise breach in 5–15 years.
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