Short answer
The static minimum bend radius is not automatically valid for dynamic use. In a dynamic application, the radius, live length and routing for the product's motion condition must be used; static and dynamic values are kept separate.
Technical explanation
The condition when a hose is bent once and remains fixed differs from the condition when it cycles continuously. For metal and other hose families, manufacturer tables may distinguish between static and dynamic radii. The reference line against which the radius is measured must also be stated. Using the externally visible bend diameter of the hose instead of the manufacturer's radius can create a measurement error. Rigid zones near the ends should not be arbitrarily counted as part of the flexible length.
Topic-specific checkpoints
| Item | Description |
|---|---|
| Static | Fixed condition, installed once |
| Dynamic | Repeated motion condition |
| Reference | Line against which the radius is measured |
| Live length | The section that can actually bend |
How is it assessed in practice?
On the layout drawing, show the most open and most closed positions of the hose together. Do not check the radius only in the starting position. Keep the 'static' or 'dynamic' label and the product code next to the value taken from the manufacturer table. If the amount of motion is unknown, do not treat a vibration that looks small as static; ask for the machine data. When the connection angle changes in a revision, re-evaluate whether the same hose length is still suitable.
Original editorial recommendation; not a clause of a standard.
Frequently asked questions
If there is no dynamic radius data, can the static value be used?
It cannot be used automatically. An assessment for the motion concerned or a suitable product recommendation must be obtained from the manufacturer.
Source coverage
-
S024
Hose and Flexible Tubing, MS-01-180 Swagelok · accessed 2026-10-19 PDF pages 4–5 / printed 253–254: Nomenclature; pages 8–9: selection, installation and use
-
S039
Hose Handling Guide Penflex · accessed 2026-10-19 Installation recommendations; overbending; twisting; supporting hose