# Air Pipe Sizing

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

## Air Pipe Sizing formula

$$\large{ d = 12 \; \sqrt { \frac { 4 } { \pi } \; \frac { Q_a } {60 \; v_a} } }$$
Symbol English Metric
$$\large{ d }$$ = pipe inside diameter $$\large{in}$$ $$\large{mm}$$
$$\large{ Q_a }$$ = air flow rate $$\large{\frac{ft^3}{min} }$$ $$\large{\frac{m^3}{min} }$$
$$\large{ v_a }$$ = air velocity $$\large{\frac{ft}{sec} }$$ $$\large{\frac{m}{s} }$$
$$\large{ \pi }$$ = Pi $$\large{3.141 592 653 ...}$$