Head loss versus flow rate variation calculator


This calculator allows us to predict, from known values of head loss and flow rate, the variation that we will have in one of these parameters when modifying the other.


Initial Conditions
Flow rate (Q)
Pressure drop (ΔP)
New Conditions
Flow rate (Q')
Pressure drop (ΔP')


The pressure drop of a system is given by the formula:
    Δp = k·ρ·Q2
    Δp = Pressure drop
    k = Resistance Coefficient (system characteristic)
    ρ = Density
    Q = Flow rate
That is, the head loss increases with the square of the flow rate. If we consider that there is no variation in density, the above equation allows us to predict these variations in a very simple way:
    Δp' = Δp x (Q’/Q)2
    Q’ = Q x (Δp'/Δp)1/2
The values of k and ρ are not relevant for these calculations since we consider that they remain constant, being cancelled in the above expressions.