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28.5 Pressure losses of Masterflex hoses
28.5.2 Pressure losses in hose bends
To supplement the specific pressure losses for hoses stretched out straight, the pressure losses in hose bends can be calculated as follows:
Pressure loss Δp=(ζρv²)/2
(Rho) ρ = density of medium (for air at 1013,2 mbar and t = 20°C: 1,21 kg/m³)
v = flow rate
(Zeta)ζ = resistance coefficient for hose bend
For circular arc bends z = 90°
| R/d |
1 |
2 |
4 |
6 |
10 |
| ζ90° |
0,36 |
0,22 |
0,17 |
0,13 |
0,15 |
Factor K for circular arc bends≠90°:
ζ=ζ90°*K
|
30° |
60° |
90° |
120° |
150° |
180° |
| K |
0,4 |
0,7 |
1,0 |
1,25 |
1,5 |
1,7 |
Example of calculation:
| Hose type: |
Master-PUR L |
| Air flow: |
10m³/min. |
| Hose DN: |
100 |
Flow rate::
(from diagram 1) |
21,2 m/s |
Specific pressure loss:
(from diagram 1) |
107 Pa/m |
| Pipe length: |
L = 10m |
- 1 x 180° bend at bend radius R = 400 (bend radius/DN≈4 → ζ=0,17)
- 1 x 90° bend at minimum permitted bend radius
(R = DN : 2 + permitted bend radius) R = 160 (bend radius/DN≈2 → ζ=0,22)
| ΔρΣ= (L * Δρ diagram)+ |
ζ90°-bend * ρ * v² |
+ |
ζ180°-bend * ρ * v² |
| 2 |
2 |
| |
| = (L * Δρ diagram)+(ζ90° + (ζ90° * K)) |
* |
ρ * v² |
| 2 |
| |
| =(10 * 107) + (0,22 + (0,17 * 1,7)) |
* |
1,21 * 21,2² |
| 2 |
| |
| = 1208,5 Pa |
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