محاسبه‌گر سایزبندی لوله HDPE

What is the intended use of the pipe?

This sets the default Manning's roughness coefficient.

Please select a use case to continue.

Design Flow Rate

Enter the peak flow rate the pipe must carry.

Flow rate (L/s)

Use the peak design flow — e.g. from a catchment hydrology calculation.

Please enter a valid positive flow rate.

Hydraulic Slope

The slope drives gravitational flow — measure along the pipe invert.

Enter slope directly

As a percentage (%) or per-mille (‰)

Enter elevation difference and length

S = Δh / L computed automatically

Slope

Enter as a percentage — e.g. "0.5" means a 0.5 m drop per 100 m of pipe.

Elevation difference Δh (m)

Drop from upstream to downstream invert.

Pipe length L (m)

Along the pipe centre-line.

Please enter a valid positive slope.

Maximum Fill Level

How full should the pipe be allowed to run under design flow?

Fill level (y/D)

75% is recommended for drainage — it provides a 25% reserve for surcharge events and allows air circulation for self-ventilation. Use 100% only for pressure-tight systems.

50% 100%

75%

Advanced Parameters

Pre-filled based on your use case — adjust only if needed.

Manning's roughness coefficient (n)

HDPE pipe (smooth bore): typically 0.009–0.011. Lower n = smoother pipe = higher flow capacity.

Please enter a Manning's n between 0.001 and 0.050.

Reference values for HDPE:
• Smooth new HDPE: n = 0.009 | • Stormwater (general): n = 0.010 | • Sewer (aged): n = 0.011