Refrigeration Piping Velocity & Pressure Drop Calculator
Size suction, discharge, and liquid lines for ammonia (R-717) and halocarbons to balance velocity, oil return, and saturated temperature pressure drop penalties.
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Hydraulic & Saturated Drop Results
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Frequently Asked Questions
Why is pressure drop in refrigeration suction lines expressed in degrees (°F)?
Refrigerant vapor is in a saturated thermodynamic state. A friction pressure drop directly reduces the pressure entering the compressor suction, which corresponds to a lower saturation temperature. In industrial refrigeration, a 1°F drop in suction saturated temperature increases compressor power consumption by approximately 1.5% to 2.0%.
What is minimum gas velocity for vertical suction risers and why is it critical?
In Halocarbon refrigeration systems (where compressor oil is miscible in the refrigerant), vertical suction risers must maintain a minimum upward gas velocity of 1,000 to 1,500 FPM at minimum compressor unloading capacity to drag entrained lubricating oil up the pipe back to the compressor crankcase, preventing compressor seizure.
Why do ammonia systems tolerate lower gas velocities than Freon systems?
Because industrial ammonia systems use non-miscible refrigeration oils that separate easily and settle by gravity into low-point oil pots and oil drain vessels (such as under low-pressure recirculator accumulators), the suction piping does not rely on gas velocity to carry oil back to the compressor.