# Flow Rate

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Flow rate, abbreviated as Q, also called volumetric flow rate, measure the amount of fluid that flows in a given time past a specific point if the temperature and pressure were at standard conditions.

## Flow Rate formula

 $$\large{ Q = A_c \; v }$$

### Where:

 Units English Metric $$\large{ Q }$$ = flow rate $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$ $$\large{ A_c }$$ = area cross-section $$\large{ft^2}$$ $$\large{m^2}$$ $$\large{ v }$$ = velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$

## Related Flow Rate formulas

 $$\large{ Q = C_v \; \sqrt {\frac{SG} {\Delta p} } }$$ (Flow Coefficient) $$\large{ Q = k \; i \; A_c }$$ (Hydraulic Gradient) $$\large{ Q = \frac{ 1.49 }{ n } \; A_c \; r_h^{2/3} \; S^{1/2} }$$ (Manning's Roughness Coefficient) $$\large{ Q = \frac{ 3960 \; WHP }{ h_t } }$$ (Water Horsepower)

### Where:

$$\large{ Q }$$ = flow rate

$$\large{ A_c }$$ = area cross-section of flow

$$\large{ S }$$ = channel slope or energy slope line

$$\large{ C_v }$$ = flow coefficient

$$\large{ k }$$ = hydraulic conductivity

$$\large{ i }$$ = hydraulic gradient

$$\large{ r_h }$$ = hydraulic radius

$$\large{ \Delta p }$$ = pressure differential

$$\large{ SG }$$ = specific gravity of fluid (water at 60°F = 1.0000)

$$\large{ h_t }$$ = total head or height

$$\large{ WHP }$$ = water horsepower