Flow restriction

[bobh]

Our SW drainage requires a 0.4l/s flow restriction before the outfall.

Now to my mind this is as simple as a capped pipe exiting a silt trap chamber with an appropriately sized hole drilled in it to give the required flow.

Do we think this would be suitable or do I need to spend a few hundred pounds on a ready made product?

 

 

 

 

 

 

[PeterW]

How big is the roof ..? And what will hold the attenuated water ..?

[bobh]

The total roof cover is 136m² 

The system has been designed with 150mm pipe rather than 110 to include a 10 m filter trench as well

[CivilEng2020]

I don't think there is a flow control with such low flow rate, I think the minimum you can get out there is 0.7 l/s. Who requires the outfall to be 0.4 l/s if I may ask?

[bobh]

14 hours ago, CivilEng2020 said:

I don't think there is a flow control with such low flow rate, I think the minimum you can get out there is 0.7 l/s. Who requires the outfall to be 0.4 l/s if I may ask?

Drainage layout was designed by our engineers along with the foundations. 

I've found a company that will supply a 0.4l/s restrictor which is essentially a silt trap with a cap on the exit pipe with an appropriately sized hole in it and then a filter fitted to it.

I'm pretty sure I could make the same myself but don't know if building inspector would ok it.

Scotland based if that makes a diffrrence