(i) $\mathrm{Re}=\frac{vD\rho }{\mu }=\frac{vD}{\nu }$

• $\mathrm{Re}$ = Reynold’s number
• $v$ = average velocity (fps)
• $D$ = pipe diameter (ft)
• $\rho$ = fluid density (slug/ft³)
• $\mu$ = kinematic viscosity (ft²/s)
• $\nu$ = dynamic viscosity (lbf⋅sec/ft² = psf·s = slug/ft·s)

---

(ii) $\mathrm{Re}=\frac{vD\gamma }{\mu }=\frac{vD}{\nu }$

• $\mathrm{Re}$ = Reynold’s number
• $v$ = average velocity (fps)
• $D$ = pipe diameter (ft)
• $\gamma$ = fluid specific weight (lb/ft³)
• $\mu$ = kinematic viscosity (ft²/s)
• $\nu$ = dynamic viscosity (lbf·sec²/ft⁴ = psf·sec²/ft²)