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K Factors for Pipe Fittings and Valves

Table 3.8: K Factors for Elbows, 90°
Size, in Regular screwed Long-radius screwed Regular flanged Long-radius flanged
½ 2.1 — — —
¾ 1.7 0.85 — —
1 1.5 0.76 0.43 —
1¼ 1.3 0.65 0.40 0.37
1½ 1.2 0.53 0.39 0.35
2 1.0 0.43 0.37 0.31
2½ 0.85 0.36 0.35 0.27
3 0.76 0.29 0.33 0.25
4 0.65 0.23 0.32 0.22
6 — — 0.29 0.18
8 — — 0.27 0.15
10 — — 0.25 0.14
12 — — 0.24 0.13
14 — — 0.23 0.12
16 — — 0.22 0.11
18 — — 0.22 0.10
20 — — 0.22 0.09
24 — — 0.21 —
Table 3.9: K Factors for Elbows, 45°
Size, in Regular screwed Long-radius flanged
½ 0.36 —
¾ 0.35 —
1 0.33 0.21
1¼ 0.32 0.20
1½ 0.31 0.18
2 0.30 0.17
2½ 0.29 0.15
3 0.28 0.14
4 0.27 0.13
6 — 0.12
8 — 0.11
10 — 0.10
12 — 0.09
14 — 0.08
16 — 0.08
Table 3.10: K Factors for Tees
Size, in Screwed-type, branch flow Flanged, line flow Flanged, branch flow
½ 2.4 — —
¾ 2.1 — —
1 1.9 0.27 1.0
1¼ 1.7 0.25 0.94
1½ 1.6 0.23 0.90
2 1.4 0.20 0.83
2½ 1.3 0.18 0.80
3 1.2 0.17 0.75
4 1.1 0.15 0.70
6 — 0.12 0.61
8 — 0.10 0.58
10 — 0.09 0.54
12 — 0.09 0.52
14 — 0.08 0.51
16 — 0.07 0.47
18 — 0.07 0.44
20 — 0.07 0.42
Table 3.11: K Factors for Globe and Gate Valves (100% open)
Size, in Globe valves (Screwed) Globe valves (Flanged) Gate valves (Screwed) Gate valves (Flanged)
½ 14 — 0.32 —
¾ 10 — 0.28 —
1 8.7 14 0.24 —
1¼ 8.0 12 0.22 —
1½ 7.5 10 0.20 —
2 6.9 8.5 0.17 —
2½ 6.5 7.9 0.15 —
3 6.0 7.0 0.14 0.22
4 5.8 6.4 0.12 0.16
6 — 5.9 — 0.11
8 — 5.7 — 0.08
10 — 5.6 — 0.06
12 — 5.6 — 0.05
14 — 5.6 — 0.05
16 — 5.6 — 0.05
18 — 5.6 — 0.04
20 — 5.6 — 0.03
Table 3.12: K Factors for Miscellaneous Valves (100% open)
Size, in Screwed check Angle valve (Screwed) Angle valve (Flanged) Ball valve* Butterfly valve
½ 5.6 — — — —
¾ 3.7 5.5 — 0.11 —
1 3.0 4.7 5.0 0.10 —
1¼ 2.7 3.8 3.7 0.09 —
1½ 2.5 3.0 3.0 0.09 —
2 2.3 2.2 2.5 0.08 —
2½ 2.2 1.7 2.3 0.07 3.5
3 2.2 1.4 2.2 0.07 3.0
4 2.2 1.0 2.2 0.06 1.5
6 — — 2.1 0.05 1.0
8 — — 2.1 0.05 0.8
10 — — 2.1 0.04 0.7
12 — — 2.1 0.04 0.7
14 — — 2.1 0.04 0.6
16 — — 2.1 0.04 0.6
18 — — 2.1 — —
20 — — 2.1 — —
Table 3.13: K Factors for Cast Iron Tapered Fittings
Pipe size, in (Large end) Pipe size, in (Small end) K Factor (As an increaser) K Factor (As a reducer)
2½ 1½ 0.11 0.05
2½ 2 0.02 0.01
3 1½ 0.18 0.07
3 2 0.07 0.04
3 2½ 0.01 0.01
4 1½ 0.34 0.12
4 2 0.21 0.08
4 3 0.04 0.02
5 2½ 0.23 0.09
5 3 0.13 0.06
5 4 0.02 0.02
6 2½ 0.34 0.13
6 3 0.24 0.10
6 4 0.09 0.05
6 5 0.01 0.01
8 4 0.26 0.11
8 5 0.13 0.07
8 6 0.05 0.03
10 6 0.18 0.08
10 8 0.03 0.02
12 6 0.31 0.13
12 8 0.11 0.06
12 10 0.02 0.02
14 6 0.42 0.16
14 8 0.22 0.10
14 10 0.08 0.05
14 12 0.01 0.01
16 10 0.16 0.08
16 12 0.05 0.04
16 14 0.01 0.01

NOTES: For screwed-type, line flow tees (Table 3.10), a K factor of 0.90 is used for all sizes. Flanged check valves (Table 3.12) are assumed to have a K factor of 2.0 for all sizes. Computed from Eqs. 3.8 and 3.9 (Table 3.13).

SOURCE: Data adapted from standard engineering references for pipe fittings and valves in HVAC and plumbing systems.

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