Hi Mohd, so sorry about the late reply, i didn't realise you had replied to my answer.   I can tell you that in irrigation (PVC) mainlines we use a maximum velocity of 1.5m/s. This is for two main reasons: 1. To reduce the risk of water hammer, and 2. To reduce any excessive friction loss in the pipe (because of increased pumping cost). In steel pipework however, I  go up to a maximum of 2.2m/s because the pipe is generally going to handle any water hammer issues better than PVC. Unfortunately, with your system we don't have any pressures (pump/pipe discharge) to work with so I can't really give you an estimate of size. If we knew the pressure differences between the pump and the discharge then we could calculate the headloss through the length of pipe and find a size. Obviously there would be a drop of 60kPa (if a static lift of 6.0m) because of the height, but this isn't anything to do with friction. I'm sorry that I can't be of any more help to you Mohd. Paul.

Published by

Hi Mohd, so sorry about the late reply, i didn't realise you had replied to my answer.

 

I can tell you that in irrigation (PVC) mainlines we use a maximum velocity of 1.5m/s. This is for two main reasons: 1. To reduce the risk of water hammer, and 2. To reduce any excessive friction loss in the pipe (because of increased pumping cost).

In steel pipework however, I  go up to a maximum of 2.2m/s because the pipe is generally going to handle any water hammer issues better than PVC.

Unfortunately, with your system we don't have any pressures (pump/pipe discharge) to work with so I can't really give you an estimate of size. If we knew the pressure differences between the pump and the discharge then we could calculate the headloss through the length of pipe and find a size.

Obviously there would be a drop of 60kPa (if a static lift of 6.0m) because of the height, but this isn't anything to do with friction. I'm sorry that I can't be of any more help to you Mohd.

Paul.