Maximum velocity of 20 ft/s in fire protection piping systems

Discussion created by rick.nunez.3000 on May 8, 2020
Latest reply on May 9, 2020 by nocivus

NFPA 13 (2020 edition) and earlier editions was silent in putting a limiting velocity in the piping along cross mains and branchlines of its sprinkler system. There are some individuals who specify that the maximum velocity shall be limited to 20 fps saying that in excess of the said velocity could create turbulence in the flow profile.  On the other hand, the turbulence constraint only apply to the discharge and suction sides of the firepump and not in the cross mains and branchlines. It a designer will opt to employ a design velocity of say 35 fps, will this yield to an unsafe design?