Larger diamiter pipe from pump

[Russ Little Pond]

My pump is a Superfish 8000, the pump has a 1.5 inch intake and a 1.5 outlet that's run on 2 inch pipe to filters, I'm pumping up about five foot, that being pump outlet to filter inlet, a run of 7 meters.

Would this run benefit from an increase in pipe size to 3 inches ?

Thanks
Russ

[Manky Sanke]

No Russ,

Increasing pipe size reduces friction losses but there is a law of diminishing returns to take into account. If you already have exceeded the recommended pipe size of 1½ inches, you will already have reduced the losses on a short section of pipe to negligible proportions. Increasing the size again won't reduce a negligible loss by anything you could measure (i.e. make it even more negligible). There is also the problem of settlement to take into account. As the pipe size increases, the speed of the water in it reduces and there is more settlement of the solids it was carrying. In a really bad case of settlement it will be deep enough to harbour anaerobic bacteria (nasty ones) or parasites such trichodina. That's why we regularly flush bottom drains to clear any settlement in the large bore pipe which has a relatively slow flow rate per square inch/cm of cross sectional area and a consequential high rate of settlement.

[Russ Little Pond]

Thanks for the reply lad.