Page 64 - HVAC Pump Handbook

Rishel_CH03.qxd 20/4/06 5:35 PM Page 61

Piping System Friction
Piping System Friction 61

TABLE 3.13 K Factors for Cast Iron Tapered Fittings
Pipe size, in K Factor
Large end Small end As an increaser As a reducer
1 1
2 ⁄ 2 1 ⁄ 2 0.11 0.05
1
2 ⁄ 2 2 1 0.02 0.01
3 1 ⁄ 2 0.18 0.07
3 2 0.07 0.04
1
3 2 ⁄ 2 0.01 0.01
1
4 1 ⁄ 2 0.34 0.12
4 2 0.21 0.08
1
4 2 ⁄ 2 0.10 0.05
4 3 0.04 0.02
1
5 2 ⁄ 2 0.23 0.09
5 3 0.13 0.06
5 4 0.02 0.02
1
6 2 ⁄ 2 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
NOTE: Computed from Eqs. 3.8 and 3.9.

1. Sudden enlargements such as screwed bushings on small pipe or
reducing-type flanges on larger pipe
2. Balance valves, manual or automatic
3. Pressure-reducing valves
4. Pressure-regulating valves
5. Bull-head tee connection
6. Multiple-duty valves
Item 5 refers to connecting a pipe tee with a supply on each run of
the tee and the discharge on the branch connection. This is a wasteful
connection and should be avoided. None of the usual references for

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