Drainage pipe capacity

[steveR]

Just looking at a drainage job to pick up an existing 6" drain (I think) and take it to a new outfall.

Just running some figures...

Am I right in saying a 160mm diam drainage pipe will carry approx 2.5 times more water than a 100mm pipe.

Real world is that two 100mm pipes in the same trench, are less money than a single 160mm. However, my suspicion is that a single pipe will have less resistance to flow...

 

[fudge]

Just looking at a drainage job to pick up an existing 6" drain (I think) and take it to a new outfall.

Just running some figures...

Am I right in saying a 160mm diam drainage pipe will carry approx 2.5 times more water than a 100mm pipe.

Real world is that two 100mm pipes in the same trench, are less money than a single 160mm. However, my suspicion is that a single pipe will have less resistance to flow...

I think you are right! 2 100mm pipes have about 3/4 of the capacity of a single 160mm pipe that’s without any increase in “resistance”.

 

[Boohoo]

Area of a circle is r²
When comparing two pipes you can remove because it's constant.
160mm pipe, 80² is 6400
100mm pipe, 50² is 2500
So yes a 160mm will carry 2.56 times as much water as a 100mm and is less likely to block than two 100mm pipes.

 

[farmerm]

Just looking at a drainage job to pick up an existing 6" drain (I think) and take it to a new outfall.

Just running some figures...

Am I right in saying a 160mm diam drainage pipe will carry approx 2.5 times more water than a 100mm pipe.

Real world is that two 100mm pipes in the same trench, are less money than a single 160mm. However, my suspicion is that a single pipe will have less resistance to flow...

watching.... I have a similar issue but mine is 75m of collapsed 9inch I am thinking a pair of 160mm will be required.

 

[spark plug]

On the flip side, what will your thought process be in several years time when your jetting two pipes instead of one

 

[North East Crofter]

watching.... I have a similar issue but mine is 75m of collapsed 9inch I am thinking a pair of 160mm will be required.

225mm carries more than twice a 150mm even better if you use twin-wall as smoother bore so less friction based on the flow calculation at 1 in 100 slope 150mm will carry 16.3 litres per second and 225mm will carry 48.2 litres per second

 

[farmerm]

225mm carries more than twice a 150mm even better if you use twin-wall as smoother bore so less friction based on the flow calculation at 1 in 100 slope 150mm will carry 16.3 litres per second and 225mm will carry 48.2 litres per second

Twin wall 225mm is per meter also about 7x the price of 160mm perforated is it not?

 

[steveR]

Area of a circle is r²
When comparing two pipes you can remove because it's constant.
160mm pipe, 80² is 6400
100mm pipe, 50² is 2500
So yes a 160mm will carry 2.56 times as much water as a 100mm and is less likely to block than two 100mm pipes.

And in a blaze of commonsense I asked my son, the lad with a Masters in Civil Engineering....

He dug out his calcs and agreed with our figure, HOWEVER, I asked him about friction effects and the larger diameter pipe is indeed much lower level of drag, so will more water will flow. I dinn't ask him the fine details [

 

[steveR]

Twin wall 225mm is per meter also about 7x the price of 160mm perforated is it not?

Fahkin expensive!!

I put about 100m in 2 years ago.

 

[Boohoo]

And in a blaze of commonsense I asked my son, the lad with a Masters in Civil Engineering....

He dug out his calcs and agreed with our figure, HOWEVER, I asked him about friction effects and the larger diameter pipe is indeed much lower level of drag, so will more water will flow. I dinn't ask him the fine details [

I just use the radius squared as a quick comparison, it's bound to be close enough for agricultural purposes.

 

[steveR]

225mm carries more than twice a 150mm even better if you use twin-wall as smoother bore so less friction based on the flow calculation at 1 in 100 slope 150mm will carry 16.3 litres per second and 225mm will carry 48.2 litres per second

The flow calcs in my case are relevant, as the fall is modest. From my first survey a month ago with my Reach RS2 GPS receiver, barely 1m in 400m! So bigger will probably win out. Am scared to ask the cost of 225mm!

Now the field is clear, I am going down (when it calms down) and explore different routes across the land, as the land rises in the middle, and it'll mean a 70-80m length of over 2m in depth

 

[milkloss]

Isn't there something about an over sized pipe not running fast enough and silting up?

 

[Wombat]

The flow calcs in my case are relevant, as the fall is modest. From my first survey a month ago with my Reach RS2 GPS receiver, barely 1m in 400m! So bigger will probably win out. Am scared to ask the cost of 225mm!

Now the field is clear, I am going down (when it calms down) and explore different routes across the land, as the land rises in the middle, and it'll mean a 70-80m length of over 2m in depth [emoji15]

The last 6inch drain I put in was 30cm in 200m

If we are putting in with the digger I only put 6” in as for the extra pipe cost might as well go as big as we can while digging the hole

160mm Perforated Land Drainage Coil (50m)

This 160mm perforated land drainage coil (50m) is ideal for use as a collector drain to aid the removal of excess surface water from gardens and fields.

store.jdpipes.co.uk

 

[Boohoo]

Isn't there something about an over sized pipe not running fast enough and silting up?

Yes, I've had that happen with a pipe that is dry at times. It's just a bridge and had used 18" concrete seconds because we had a couple sitting. Had to take them out and replace with 12" twinwall.

 

[steveR]

On the flip side, what will your thought process be in several years time when your jetting two pipes instead of one

Don't jet pipes around here...

 

[steveR]

Isn't there something about an over sized pipe not running fast enough and silting up?

But the argument, is that a big pipe will keep running longer....

 

[steveR]

The last 6inch drain I put in was 30cm in 200m

If we are putting in with the digger I only put 6” in as for the extra pipe cost might as well go as big as we can while digging the hole

160mm Perforated Land Drainage Coil (50m)

This 160mm perforated land drainage coil (50m) is ideal for use as a collector drain to aid the removal of excess surface water from gardens and fields.

store.jdpipes.co.uk

The extra price cost is double that of 100mm, but 160mm may be a better job for me...

Not a bad price... have found a bit cheaper locally mind.

 

[farmerm]

The last 6inch drain I put in was 30cm in 200m

If we are putting in with the digger I only put 6” in as for the extra pipe cost might as well go as big as we can while digging the hole

160mm Perforated Land Drainage Coil (50m)

This 160mm perforated land drainage coil (50m) is ideal for use as a collector drain to aid the removal of excess surface water from gardens and fields.

store.jdpipes.co.uk

can you find me some 225mm for similar money...

 

[Wombat]

The extra price cost is double that of 100mm, but 160mm may be a better job for me...

Not a bad price... have found a bit cheaper locally mind.

Yup i know its double but my bucket is 6" bottom and in the end for us getting a tonne of corn back per 50m with a 6"drain doesn't take long,

 

[Wombat]

can you find me some 225mm for similar money...

i have a quote for some 1200mm and 1500mm twinwall on my desk .......