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Friction Loss Tables

Friction Losses in Pipe Fittings
Resistance Coefficient K (use in formula hf = Kv2/2g)
Fitting LD Nominal Pipe Size
1/2" 3/4" 1 1-1/4" 1-1/2" 2 2-1/2"-3 4 6 8-10 12-16 18-24
K Value
Angle Valve 55 1.48 1.38 1.27 1.21 1.16 1.05 0.99 0.94 0.83 0.77 0.72 0.66
Angle Valve 150 4.05 3.75 3.45 3.30 3.15 2.85 2.70 2.55 2.25 2.10 1.95 1.80
Ball Valve 3 0.08 0.08 0.07 0.07 0.06 0.06 0.05 0.05 0.05 0.04 0.04 0.04
Butterfly Valve             0.86 0.81 0.77 0.68 0.63 0.35 0.30
Gate Valve 8 0.22 0.20 0.18 0.18 0.15 0.15 0.14 0.14 0.12 0.11 0.10 0.10
Globe Valve 340 9.2 8.5 7.8 7.5 7.1 6.5 6.1 5.8 5.1 4.8 4.4 4.1
Plug Valve Branch Flow 90 2.43 2.25 2.07 1.98 1.89 1.71 1.62 1.53 1.35 1.26 1.17 1.08
Plug Valve Straightaway 18 0.48 0.45 0.41 0.40 0.38 0.34 0.32 0.31 0.27 0.25 0.23 0.22
Plug Valve 3-Way Thru-Flow 30 0.81 0.75 0.69 0.66 0.63 0.57 0.54 0.51 0.45 0.42 0.39 0.36
Standard Elbow 90° 30 0.81 0.75 0.69 0.66 0.63 0.57 0.54 0.51 0.45 0.42 0.39 0.36
45° 16 0.43 0.40 0.37 0.35 0.34 0.30 0.29 0.27 0.24 0.22 0.21 0.19
long radius
90°
16 0.43 0.40 0.37 0.35 0.34 0.30 0.29 0.27 0.24 0.22 0.21 0.19
Close Return Bend 50 1.35 1.25 1.15 1.10 1.05 0.95 0.90 0.85 0.75 0.70 0.65 0.60
Standard Tee Thru-Flow 20 0.54 0.50 0.46 0.44 0.42 0.38 0.36 0.34 0.30 0.28 0.26 0.24
Thru-Branch 60 1.62 1.50 1.38 1.32 1.26 1.14 1.08 1.02 0.90 0.84 0.78 0.72
90 Bends,
Pipe Bends,
Flanged Elbows,
Butt-Welded
Elbows
r/d=1 20 0.54 0.50 0.46 0.44 0.42 0.38 0.36 0.34 0.30 0.28 0.26 0.24
r/d=2 12 0.32 0.30 0.28 0.26 0.25 0.23 0.22 0.20 0.18 0.17 0.16 0.14
r/d=3 12 0.32 0.30 0.28 0.26 0.25 0.23 0.22 0.20 0.18 0.17 0.16 0.14
r/d=4 14 0.38 0.35 0.32 0.31 0.29 0.27 0.25 0.24 0.21 0.20 0.18 0.17
r/d=6 17 0.46 0.43 0.39 0.37 0.36 0.32 0.31 0.29 0.26 0.24 0.22 0.20
r/d=8 24 0.65 0.60 0.55 0.53 0.50 0.46 0.43 0.41 0.36 0.34 0.31 0.29
r/d=10 30 0.81 0.75 0.69 0.66 0.63 0.57 0.54 0.51 0.45 0.42 0.39 0.36
r/d=12 34 0.92 0.85 0.78 0.75 0.71 0.65 0.61 0.58 0.51 0.48 0.44 0.41
r/d=14 38 1.03 0.95 0.87 0.84 0.80 0.72 0.68 0.65 0.57 0.53 0.49 0.46
r/d=16 42 1.13 1.05 0.97 0.92 0.88 0.80 0.76 0.71 0.63 0.59 0.55 0.50
r/d=18 45 1.24 1.15 1.06 1.01 0.97 0.87 0.83 0.78 0.69 0.64 0.60 0.55
r/d=20 50 1.35 1.25 1.15 1.10 1.05 0.95 0.90 0.85 0.75 0.70 0.65 0.60
Mitre Bends a=0° 2 0.05 0.05 0.05 0.04 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.02
a=15° 4 0.11 0.10 0.09 0.09 0.08 0.08 0.07 0.07 0.06 0.06 0.05 0.05
a=30° 8 0.22 0.20 0.18 0.18 0.17 0.15 0.14 0.14 0.12 0.11 0.10 0.10
a=45° 15 0.41 0.38 0.35 0.33 0.32 0.29 0.27 0.26 0.23 0.21 0.20 0.18
a=60° 25 0.68 0.63 0.58 0.55 0.53 0.48 0.45 0.43 0.38 0.35 0.33 0.30
a=75° 40 1.09 1.00 0.92 0.88 0.84 0.76 0.72 0.68 0.60 0.56 0.52 0.48
a=90° 60 1.62 1.50 1.38 1.32 1.26 1.14 1.08 1.02 0.90 0.84 0.78 0.72
Note: Fittings are standard with full openings.

Fitting L/D Minimum
Velocity for
Full Disc Lift
Nominal Pipe Size
1/2" 3/4" 1 1-1/4" 1-1/2" 2 2-1/2"-3 4 6 8-10 12-16 18-24
General
ft/sec
Water
ft/sec
K Value
Swing Check Valve 100 35 4.40 2.70 2.50 2.30 2.20 2.10 1.90 1.80 1.70 1.50 1.40 1.30 1.20
50 48 6.06 1.40 1.30 1.20 1.10 1.10 1.00 0.90 0.90 0.75 0.70 0.65 0.60
Lift Check Valve 600 40 5.06 16.2 15.0 13.08 13.2 12.6 11.4 10.8 10.2 9.0 8.4 7.8 7.2
55 140 17.7 1.50 1.40 1.30 1.20 1.20 1.10 1.00 0.94 0.83 0.77 0.72 0.66
Tilting Disc Check Valve 5 80 10.13           0.76 0.72 0.68 0.60 0.56 0.39 0.24
15 30 3.80           2.30 2.20 2.00 1.80 1.70 1.20 0.72
Foot Valve with Strainer
Poppet Disc
420 15 1.90 11.3 10.5 9.70 9.30 8.80 8.00 7.60 7.10 6.30 5.90 5.50 5.0
Foot Valve with Strainer
Hinged Disc
75 35 4.43 2.00 1.90 1.70 1.70 1.70 1.40 1.40 1.30 1.10 1.10 1.00 0.90

Fitting Description All Pipe Sizes
K Value
Pipe Exit Projecting
Sharp-Edged
Rounded
1.00
Pipe Entrance Inward Projecting 0.78
Pipe Entrance Flush Sharp-Edged 0.50
r/d=0.02 0.28
r/d=0.04 0.24
r/d=0.06 0.15
r/d=0.10 0.09
r/d<0.14 0.04

The K values given below are for making estimates of friction loss in cases not covered in the previous tables.

Type of Fitting K Value
Disk or Wobble Meter 3.4 - 10
Rotary Meter (Star or Cog-Wheel Piston) 10
Reciprocating Piston Meter 15
Turbine Wheel (Double-Flow) Meter 5 - 7.5
Bends w/Corrugated Inner Radius 1.3 - 1.6 times value for smooth bend
Example: Determine L (friction loss in pipe fittings in terms of equivalent length
in feet of straight pipe).
Assume a 6" angle valve for Schedule 40 pipe size.
Select the appropriate K value for such and select D and f for Schedule 40 pipe
from the table below where K is the pipe diameter in feet.
Pipe Size
Inches
Sch. 40
D
feet
f Pipe Size
Inches
Sch. 40
D
feet
f Pipe Size
Inches
Sch. 40
D
feet
f Pipe Size
Inches
Sch. 40
D
feet
f
1/2"
3/4"
1
1-1/4"
1-1/2"
2
0.0518
0.0687
0.0874
0.1150
0.1342
0.1723
0.027
0.025
0.023
0.022
0.021
0.019
2-1/2"
3
4
5
6
8
0.2058
0.2557
0.3355
0.4206
0.5054
0.6651
0.018
0.018
0.017
0.016
0.015
0.014
10
12
14
16
18
20
0.8350
0.9948
1.0937
1.250
1.4063
1.5678
0.014
0.013
0.013
0.013
0.012
0.012
24
30
36
42
48
1.8857
2.3333
2.8333
3.3333
3.8333
0.012
0.011
0.011
0.010
0.010

Friction Loss of Water in Pipe Fittings in Terms of Equivalent
Length - Feet of Straight Pipe
Nominal
pipe size
Actual
inside
diameter
inches
d
Friction
factor
f
Gate
valve
-
full
open
90°
elbow
Long
radius
90° or
45° sth
elbow
Sth
tee
-
thru
flow
Sth
tee
-
branch
flow
Close
return
bend
Swing
check
valve
-
full open
Angle
valve
-
full
open
Globe
valve
-
full
valve
Butter-
fly valve
90°Welding
elbow
Mitre bend
r/d = 1 r/d = 2 45° 90°
1/2"
3/4"
1
1-1/4"
1-1/2"
.622
.824
1.049
1.380
1.610
.027
.025
.023
.022
.021
.41
.55
.70
.92
1.07
1.55
2.06
2.62
3.45
4.03
.83
1.10
1.40
1.84
2.15
1.04
1.37
1.75
2.30
2.68
3.11
4.12
5.25
6.90
8.05
2.59
3.43
4.37
5.75
6.71
5.18
6.86
8.74
11.5
13.4
7.78
10.3
13.1
17.3
20.1
17.6
23.3
29.7
39.1
45.6
         
2
2-1/2"
3
4
5
2.067
2.469
3.068
4.026
5.047
.019
.018
.018
.017
.016
1.38
1.65
2.04
2.68
3.36
5.17
6.17
7.67
10.1
12.6
2.76
3.29
4.09
5.37
6.73
3.45
4.12
5.11
6.71
8.41
10.3
12.3
15.3
20.1
25.2
8.61
10.3
12.8
16.8
21.0
17.2
20.6
25.5
33.6
42.1
25.8
30.9
38.4
50.3
63.1
58.6
70.0
86.9
114
143
7.75
9.26
11.5
15.1
18.9
3.45
4.12
5.11
6.71
8.41
2.07
2.47
3.07
4.03
5.05
2.58
3.08
3.84
5.03
6.31
10.3
12.3
15.3
20.1
25.2
6
8
10
12
14
6.065
7.981
10.02
11.938
13.124
.015
.014
.014
.013
.013
4.04
5.32
6.68
7.96
8.75
15.2
20.0
25.1
29.8
32.8
8.09
10.6
13.4
15.9
17.5
10.1
13.3
16.7
19.9
21.8
30.3
39.9
50.1
59.7
65.6
25.3
33.3
41.8
49.7
54.7
50.5
33.3
41.8
49.7
54.7
75.8
99.8
125
149
164
172
226
284
338
372
22.7
29.9
29.2
34.8
38.3
10.1
13.3
16.7
19.9
21.8
6.07
7.98
10.0
11.9
13.1
7.58
9.98
12.5
14.9
16.4
30.3
39.9
50.1
59.7
65.6
16
18
20
24
30
15.00
16.876
18.814
22.628
28
.013
.012
.012
0.12
.011
10.0
16.9
12.5
15.1
18.7
37.5
42.2
47.0
56.6
70
20.0
22.5
25.1
30.2
37.3
25.0
28.1
31.4
37.7
46.7
75.0
84.4
94.1
113
140
62.5
70.3
78.4
94.3
117
62.5
70.3
78.4
94.3
188
210
235
283
425
478
533
641
31.3
35.2
39.2
47.1
25.0
28.1
31.4
37.7
46.7
15.0
16.9
18.8
22.6
28
18.8
21.1
23.5
28.3
35
75.0
84.4
94.1
113
140
36
42
48
34
40
46
.011
.010
.010
22.7
26.7
30.7
85
100
115
45.3
53.3
61.3
56.7
66.7
76.7
170
200
230
142
167
192
        56.7
66.7
76.7
34
40
46
43
50
58
170
200
230
L/D 8 30 16 20 60 50 1/2" to 6
= 100
24 to 48
=50
150 340   20 12 15 60

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