Refrigerant Line Velocity Calculator

Velocity matters for oil return in suction and discharge risers and for pressure drop.

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Density must come from verified refrigerant property data at line conditions.

Formula

v = ṁ ÷ (ρ × A)
A = π × d² ÷ 4

Example calculation

0.05 kg/s of vapour at 30 kg/m³ in a 19.9 mm ID line ≈ 5.4 m/s (1,060 fpm).

Practical HVAC use

Check a line against the manufacturer's minimum velocity for oil return.

Common mistakes

Using outside diameter instead of inside diameter.

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Educational tool. Results are estimates from the stated formulas; always confirm with manufacturer data and the code adopted in your jurisdiction. All calculators