Installation Guide

45
Pressure Flow
Friction loss through PVC pipe is normally obtained by using
theHazen-Williamsequationshownbelowforwater:
f = 0.2083 x
(
100
)
1.852
x Q
1.852
C di
4.8655
Where:
f =frictionheadlossinfeetofwaterper100feetofpipe
C =constantforinsidepiperoughness(C=150forABS
and PVC pipe)
Q =owinU.S.gallonsperminute
di=insidediameterofpipeininches
Friction Loss Through Fittings
The friction loss through fittings is considered to be equivalent to the loss through a certain number of linear feet of pipe of
thesamediameterasthettings.Todeterminethelossthroughapipingsystem,addtogetherthenumberof“equivalentfeet”
calculated for the fittings in the system.
Thechartbelowshowsapproximatefrictionlosses,inequivalentfeet,foravarietyofSchedule40&80PVCandCPVCttings
ofdifferentsizes.
The table on page 47 shows friction heads in feet and friction losses in psi for schedule 40 pipe. It also shows the gallons per
minute(GPM)andvelocities(infeetpersecond)forvariouspipesizes.
Fitting
1
⁄2 ”
3
⁄4 ” 1 ” 1
1
⁄4 ” 1
1
⁄2 ” 2 ” 2
1
⁄2 ” 3 ” 4 ” 6 ” 8 ”
Tee (Run) 1.0 1.4 1.7 2.3 2.7 4.3 5.1 6.2 8.3 12.5 16.5
Tee (Branch) 4.0 5.0 6.0 7.3 8.4 12.0 15.0 16.4 22.0 32.7 49.0
90° Elbow 1.5 2.0 2.5 3.8 4.0 5.7 6.9 7.9 12.0 18.0 22.0
45° Elbow .80 1.1 1.4 1.8 2.1 2.6 3.1 4.0 5.1 8.0 10.6
 Male/FemaleAdapter 1.0 1.5 2.0 2.75 3.5 4.5 5.5 6.5 9.0 14.0 —
Approximate Friction Loss For PVC and CPVC Fittings In Equivalent Feet Of Straight Pipe
Water Velocities
Water velocities in feet per second may be calculated as
follows:
V = 0.408709 Q
di
2
Where:
V =velocityinfeetpersecond
Q =owinU.S.gallonsperminute
di=insidediameterofpipeininches
DESIGN & ENGINEERING DATA