During normal operations, to know if there is discoloration risk you have to look at the results of the whole day and look for the maximum velocity:
- <0.3 m/s max velocity cause sedimentation
- From 0.3 to 0.8 m/s max velocity pipes are “self-cleansing”, they don’t accumulate sediments.
And if you are performing flushing events:
- From 0.8 to 1.5 m/s could be a good flushing velocity, but in some cases not enough to remove biofilm
- >3 m/s is considered too much speed, which can cause issues in the network
- If there’s a big increase in velocity: from less than 0.2 (max vel during the day) to 0.8 m/s in any direction, it will allow for particule resuspension and could affect discoloration
- The flow direction is reversed and the current velocity is >= 0.1m/s