Pipe DN Recommendation
Input Data
Enter your project data
System type automatically sets velocity limits (and, for Heating/Cooling, a verified friction-rate target). Heating/cooling are sized primarily on friction loss; fire lines by a velocity ceiling that depends on the pipe role (no minimum velocity).
Switch to "Calculate from Heat Load" to size the pipe from kW + ΔT instead of typing m³/h directly. Only available when System Type is Heating/Cooling.
Total flow rate through the pipe
Heating or cooling capacity carried by this pipe
ΔT for heating/cooling systems (typically 20°C for heating, 5-6°C for chilled water — e.g. 80/60°C heating or 6/12°C chilled water)
Used only for density in the heat-load-to-flow conversion. Heating: 70-80°C, Chilled water: 6-12°C
Pipe material affects inner diameter and roughness
Calculation Results
Calculated instantly from your inputs
Smart Diameter Selection
This calculator recommends the optimal pipe diameter based on your system type and flow requirements.
Each system has specific velocity limits:
- HVAC: 0.5-1.5 m/s (noise control)
- Fire: by pipe role — feed main 5, cross main 8, branch line 15 m/s max; no minimum; Hazen-Williams C = 120 steel / 150 copper and plastic
- Water: 0.6-2.0 m/s (balanced)
- Compressed Air: 6-12 m/s (high velocity OK)
Key Points:
- System-specific velocity limits
- Automatic standard pipe selection
- Alternative options provided
- Head loss calculation included
Calculation Steps:
- Enter all required parameters
- Click "Update Calculation"
- Review results and analysis
Formula Variables:
D
Diameter
(mm)
Q
Flow Rate
(m³/h)
V
Velocity
(m/s)
Re
Reynolds
(-)
f
Friction Factor
(-)