Saturday, November 5, 2022

Head Loss in Innovyze H2OCalc

 

3.7 Head loss due to Transitions and Fittings (Local loss)

Whenever flow velocity changes direction or magnitude in a conduit (e.g., at fittings, bends, and other appurtenances) added turbulence is induced. The energy associated with that turbulence is eventually dissipated into heat that produces a minor head loss, or local (or form) loss. The local (minor) loss associated with a particular fitting can be evaluated by

                                                                                                      

where   V         =          mean velocity in the conduit (m/s, ft/s)

                K         =          loss coefficient for the particular fitting involved.

The table given below provides the loss coefficients (K) for various transitions and fittings.

 

Table 3-3: Typical Minor Loss Coefficients

Type of form loss

K

Expansion

Sudden

D1 < D2

Gradual

D1/D2 = 0.8

0.03

D1/D2 = 0.5

0.08

D1/D2 = 0.2

0.13

Contraction

Sudden

D1 > D2

Gradual

D2/D1 = 0.8

0.05

D2/D1 = 0.5

0.065

D2/D1 = 0.2

0.08

Pipe entrance

Square-edge

0.5

Rounded

0.25

Projecting

0.8

Pipe exit

Submerged pipe to still water

1.0

Tee

Flow through run

0.6

Flow through side outlet

1.8

Orifice

(Pipe diameter

 /orifice diameter)

D/d = 4

4.8

D/d = 2

1.0

D/d = 1.33

0.24

Venturi (long-tube)

(Pipe diameter

 /throat diameter)

D/d = 3

1.1

D/d = 2

0.5

D/d = 1.33

0.2

Bend

90o miter bend with vanes

0.2

90o miter bend without vanes

1.1

45o miter bend

0.2

Type of form loss (continued)

K

Bend

45o smooth bend:

     (bend radius

 /pipe diameter)

r/D = 1

0.37

r/D = 2

0.22

r/D = 4

0.2

90o smooth bend

r/D = 1

0.5

r/D = 2

0.3

r/D = 4

0.25

Closed return bend

2.2

Sluice

Submerged port in wall

0.8

As conduit contraction

0.5

Without top submergence

0.2

Valve

Globe valve, fully open

10

Angel valve, fully open

5.0

Swing check valve, fully open

2.5

Gate valve, fully open

0.2

Gate valve, half open

5.6

Butterfly valve, fully open

1.2

Ball valve, fully open

0.1

       Source: Nicklow and Boulos (2005)


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