Choosing the right pipe size – and the right flow meter size – starts with the flow range by pipe size. The chart below gives typical flow ranges for each nominal pipe diameter (DN), helping engineers size pipes, valves and flow meters correctly.
How flow, velocity and pipe size are related
Volumetric flow is Q = v × A, where v is the mean velocity and A the internal cross-section of the pipe. For a pipe of internal diameter d (m): Q (m³/h) = 3600 × v × π × d² / 4.
| Medium | Typical design velocity |
|---|---|
| Water / liquids | 1 – 3 m/s |
| Saturated steam | 15 – 40 m/s |
| Compressed air | 6 – 10 m/s |
| Gases (low pressure) | 10 – 20 m/s |
Velocities outside these ranges cause noise, erosion and high pressure drop (too fast) or oversized, costly pipes (too slow). Note that a flow meter is sized by actual flow and pressure – not necessarily equal to pipe size. See the flow tables in our vortex flow meter article.
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Where to buy flow meters?
EQUIPMENT INDUSTRIAL SOLUTION CO., LTD (ISE) – Ho Chi Minh City, Vietnam – supplies genuine flow meters with technical consulting, fast quotation and on-site commissioning support across Vietnam and Southeast Asia.
Contact us: Sales +84 909 617 185 – Technical +84 979 117 185 – Email: [email protected]
