Pressure losses
Determining the pressure loss of a hose line
When conveying media, friction losses inevitably occur and must be taken into account when determining the required compressor performance. Our hoses are optimised for flow, particularly smooth, and fold evenly on the inner bending radius, so that losses are reduced to a minimum. This lowers both the investment and operating costs of the overall system.
The total pressure loss is made up of a first component Δpᵥ, which can be taken from the diagrams, and a second componentΔpbend, which must be considered and calculated when routing through bends.
- l = hose length
- ζ = resistance coefficient, see below
- ρ = density, e.g. for air 1.21 kg/m³
- v = flow velocity
Δpv,Σ = (l⋅Δpv) + Δpbend = (l⋅Δpv) + (ζbend 1 + ζbend 2 + ⋯ + ζbend n) ⋅ (ρ/2) ⋅ v2
The resistance coefficient ζ must be determined individually for each bend and then inserted into the formula above:
ζbend = k ⋅ ζ90°
| Angle of curvature φ | 30° | 60° | 90° | 120° | 150° | 180° |
| k | 0.4 | 0.7 | 1.0 | 1.25 | 1.5 | 1.7 |
| Bending radius / internal Ø | 1 | 2 | 4 | 6 | 10 |
| ζ90° | 0.51 | 0.3 | 0.23 | 0.18 | 0.2 |
Example
Pressure loss of a Ø 75 mm AIRDUC PUR® 351 FOOD hose
- at a flow velocity of 19 m/s (i.e. determined from the diagram: Δpᵥ = 120 Pa/m),
- with a hose length of 12 m and
- one 90° bend executed with the permissible minimum bend radius (i.e. bend radius + ½ × internal Ø / internal Ø ≈ 1 → ζ₉₀° = 0.51; φ = 90° → k = 1), and
- one 180° bend laid with twice the minimum bend radius (→ ζ₉₀° = 0.3; φ = 180° → k = 1.7):
Δpv,Σ = (12 m · 120 Pa/m) + (1 · 0,51 + 1,7 · 0,3) · 1/2 · 1,21 kg/m³ · (19 m/s)² = 1440 Pa + 223 Pa = 1663 Pa
Average values of Δpv for the following hose types:
- AIRDUC® 341, 350, 351, 352, 362, 363
- AIRDUC® 356
- BARDUC® 381, 382
- NEO 2, SIL 2
- TIMBERDUC® 533
- NORPLAST® 379 - 380, 383 - 389
- AIRDUC® 345, 355
- AIRDUC® 357
- NEO 1, SIL 1
- PROTAPE® 326, 327
- TIMBERDUC® 534
- PROTAPE® 310, 322, 370, 371
- PROTAPE® 301, 330, 332
- TIMBERDUC® 531, 532
- CP 450 - 487
- SuperFlex 372
- EVA 373
As the operating conditions at the user’s site are beyond our control and the design variations are too extensive, no guarantee can be given for the accuracy of the stated values.
Subject to technical modifications.