Duct Pressure Drop Calculator

This duct pressure drop calculator is a tool to assist in estimating the pressure drop in an HVAC ducts.
CalculationInputs﻿﻿Density of Air, kg/m3
:1​
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﻿﻿Air Stream Velocity, m/s
:1​
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﻿﻿Loss Coefficient
:0.5​
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Output﻿﻿Velocity Pressure
:0.5Pa​
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﻿﻿Pressure Loss
:0.25Pa​
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ExplanationDuct system pressure drop is calculated using the velocity pressure of the duct and the loss coefficient for the particular duct components. The ducts velocity pressure is calculated using the density of air flowing through the duct and the velocity of this air stream.
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PT=KT∗PVP_T = K_T*P_VPT​=KT​∗PV​
Where:
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PT=Total pressure loss through fittings (Pa)KT=Loss coefficientPV=Velocity pressure (Pa)P_T = Total \: pressure \: loss \: through \: fittings \: (Pa)          \\ K_T = Loss \: coefficient                                                                    \\ P_V = Velocity \: pressure \: (Pa)PT​=Totalpressurelossthroughfittings(Pa)KT​=LosscoefficientPV​=Velocitypressure(Pa)
To calculate the velocity pressure we use the following equation:
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PV=0.5∗ρV2P_V = 0.5*\rho V^2PV​=0.5∗ρV2
Where:
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ρ=Density of air (kgm−3)V=Velocity of air stream (ms−1)\rho = Density \: of \: air \: (kgm^{-3})                                                 \\V = Velocity \: of \: air \: stream \: (ms^{-1})ρ=Densityofair(kgm−3)V=Velocityofairstream(ms−1)
Related ResourcesCheck out our full library of CalcTree templates here!
Air Duct Velocity
Rate of Ventilation (Area Method)
Rate of Ventilation (Occupancy Method)
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