Pipe Diameter calculator

Design Philosophy

The economic and hydraulic design of a water supply pipeline depends critically on the selection of an appropriate pipe diameter. The CPHEEO Manual on Water Supply prescribes that the pipe diameter shall be determined by the design flow and a design flow velocity that is within the recommended range to prevent both sedimentation and excessive head loss. The governing equation is the continuity equation of flow:

Recommended Velocity Range (CPHEEO Manual on Water Supply)

The CPHEEO Manual recommends that the velocity in water supply mains shall be maintained between 0.6 m/s (minimum, to prevent silting) and 3.0 m/s (maximum, to limit head loss and water hammer). For rising mains, a design velocity of 1.0 to 1.8 m/s is generally adopted. For gravity mains, velocities of 0.6 to 1.2 m/s are typical.

Diameter Calculation

For a circular pipe, the cross-sectional area is:

Substituting into the continuity equation and solving for diameter:

The calculated diameter is a theoretical minimum. In practice, the designer selects the next available nominal bore (NB) from the standard pipe schedule. The calculator presents the result in millimeters and inches for reference to both IS pipe schedules and international standards.

Unit Conversion

The calculator accepts flow inputs in multiple units (MLD, m³/day, m³/hr, m³/s, GPM, LPM, LPS, MGD) and velocity inputs in m/s, ft/s, cm/s, and mm/s, with automatic conversion to SI base units for all calculations.

Calculator

(Note – all Yellow are user defined value, all white are fixed values, all green are calculated value, all orange is calculated not to be shown)

Instructions

Enter values highlighted in the Yellow

Green highlights are the results

In case of any invalid result of non-functioning of the calculator, please write to us at design@swaenviro.com. We will try and help you with your sizing and calculation

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