YS-INF-WR-01

WATER PIPE DESIGN

Problem

Design a water pipe that meant to carry 2MLPD of water demand and 3 nos. of fire flow. Use peak flow factor 1.2 (for incoming main).

Solution

1. Calculate the design peak flow by multiplying peak flow factor to water demand.
2. Calculate total fire flow by multiplying the number of fire flow to 300gpm (approximately 1,963,911lpd). Then, calculate the design fire flow by adding the water demand to total fire flow.
3. Determine the pipe material, referring to cl.B4.1(B), SPAN-UTG.
4. Set water pipe diameter. Identify the internal diameter of pipe based on relevant standard or catalogue.
5. Determine Hazen-Williams coefficient based on Table B.7, SPAN-UTG.
6. Calculate full pipe flow velocity using Hazen-Williams equation for both conditions i.e. peak flow and fire flow.
7. Check whether the velocity through water pipe lies between 0.3m/s to 2.0m/s, which is the acceptable range based on cl.B4.1-C(iv), SPAN-UTG.
8. Calculate headloss through pipe using Hazen-Williams headloss equation for both conditions. Then, convert the unit calculated headloss to m/km.
9. Check whether the headloss gradient through water pipe is less than 2m/km for peak flow, or 15m/km for fire flow, as per cl.B4.1-C(i) & (ii), SPAN-UTG.