TECHNICAL FEATURE 1. Determine required pipe diameter using Equation 4a: dC * = 3 mv V (4a) where d = pipe inside diameter, in.(mm) C3= 3.0984 (I-P), 33.333 (SI), dimensionless ṁ = mass flow rate, lbm/h(kg/h) υ = specific volume, ft3/lbm(m3/kg) V = steam velocity, fpm(m/s) 2. Select the closest standard pipe size with at least the internal pipe diameter calculated in step 1. 3. Determine the resulting steam velocity using the selected inside pipe diameter from step 2 and Equation 4b, a rearranged form of Equation 4a from step 1: V = mv dhttp://ashrae.org