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 optimized for flow, feature particularly smooth surfaces, and fold evenly along the inner bend radius. This minimizes losses and reduces both capital and operating costs of the overall system.
The total pressure loss consists of a first component Δpᵥ, which can be taken from the diagrams, and a second component Δpbend, which must be considered and calculated when routing through bends.
- l = hose length
- ζ = loss 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 loss 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 an AIRDUC PUR® 351 FOOD hose, Ø 75 mm
- 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,
- with one 90° bend executed at 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 installed at 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 operating conditions at the user’s site are beyond our control and the range of design variations is too large, no guarantee can be given for the accuracy of the stated values.
Subject to technical modifications.