When designing a metal hose assembly, flow velocity should be taken into consideration.

Click here to use our Flow Velocity Calculator

Flow Velocity is given by:


v       = Flow Velocity

qv     = Volumetric Flow Rate

qm   = Mass Flow Rate

di        = Internal Diameter of Metal Hose in mm

p        = Medium Density


Please Note:

The Flow Velocity in a corrugated metal hose should never exceed 45m/sec for gas or 23m/sec for liquids. High Velocities can force the corrugations into resonant vibration; this can result in premature failure – such failures can be prevented through the use of an internal liner or change in the nominal size. The critical speed is mostly influenced by the medium conveyed and its working conditions, the shape of the corrugations and hose bending. It can start from 5m/s for liquids and 30m/s for gases. For higher values, it is intended that the manufacturer be consulted. (BS EN ISO 10380-2012)


This chart illustrates that Velocity varies with regards to whether the metal hose has a bend in it.

(without Liner) m/sec
Liquid Straight 23
Liquid 45 deg Bend 17
Liquid 90 deg Bend 11
Gas Straight 45
Gas 45 deg Bend 34
Gas 90 deg Bend 23