Fittings adversely affect the friction loss through a piping system. However, often less than a person may assume. With these two charts you can calculate the approximate amount of friction loss for a fitting by determining the approximate feet of pipe a fitting is equivalent too. Add up the total Base Footage for all your suspect fittings from chart (1), Multiply by the “Multiplying Factors to Convert Base Footage Equivalents to Footage Equivalents for Specific Pipe” Chart 2, and then look at a friction loss chart for the particular type of pipe and use that to determine the actual friction loss of those components CHART 1 Base Footage Equivalent Fitting TypeNominal Pipe Size: Inches .5 (1/2).75 (3/4)11.25 (1-1/4)1.5 (1-1/2)22.5 (2-1/2)34681012 Base Footage Equivalent: Numbers below are the “Base Footage Equivalents” of pipe for each of the fittings. Make sure you use the multiplier in CHART 2 below to convert this figure to the actual footage equivalent for the type of pipe you are using. Gate valve0.70.91.11.51.72.22.73.34.46.68.610.912.9 Spring Check valve79.311.815.518.123.327.834.545.368.289.8112.7134.3 90 Deg Ell1.62.12.63.545.26.27.710.115.22025.129.9 45 Deg Ell0.81.11.41.82.22.83.34.15.48.110.613.415.9 Run of Straight Tee11.41.82.32.73.54.15.16.710.113.316.719.9 Branch of Straight Tee3.14.15.36.98.110.312.415.320.130.339.950.159.7 Reducing Bushing 1 Sizena1.61.52.51.73.51.748.132.119.815.210.4 Reducing Bushing 2 Sizenana7.710.57.88.912.413.632.5123.2175.2102.168.3 Increasing Bushing 1 Size0.40.50.70.310.71.42.25.55.254.4na Increasing Bushing 2 Size0.71.21.31.62.12.64.27.510.512.212.1nana                CHART 2 Multiplying Factors to Convert Base Footage Equivalents to Footage Equivalents for Specific Pipes Kind of PipeNominal Pipe Size: Inches .5 (1/2).75 (3/4)11.25 (1-1/4)1.5 (1-1/2)22.5 (2-1/2)34681012 Multiply Base Footage Equivalent by these Multiplying Factors to calculate your actual footage to be used with a friction loss chart to calculate actual friction loss. SDR111.42nananananananananananana SDR21na1.841.921.611.481.311.411.281.161.040.990.950.93 SCH400.971.011.031.061.071.081.081.091.11.111.111.111.11 Controlled ID Poly Pipe111111nanananananana                EXAMPLE: A pond project using 6″ SDR21 @ 400GPM with (5) 6″ 90’s and (4) 6″ 45’s. (5) 90’s (5 x 15.2) = 76 Base Footage, (4) 45’s (4 x 8.1) = 32.4 Base Footage. A total of (76 + 32.4) 108.4 Base Footage. 108.4 x Multiplying Factor of 1.04 = 112.74 actual feet of pipe. At 400 GPM the friction loss through 6″ SDR21 is .46PSI per 100′. 112.74 / 100′ = 1.128 (100′ lengths) x .46 = .519 PSI loss through the fittings.