confirmation please

[breezer]

mate and i were haveing a debate

can any one confirm / deny the follwing to be true

which gives the most flow

2 x 1 inch pipes

1 x 2 inch pipe

I opted for the 1, 2 inch pipe becuse its 2 inch.

mate said i was right, but i could not say exactly why.

so he said think of it like this

2 1 inch pipes will (in theory) fit inside a 2 inch pipe, but you have also got the space around the top/ bottom of each pipe

(being round there is space left at the top and bottom)

 

[namsag]

Why not just work out the area of a circle this will answer your question... double the size quadruple the area

 

[ChrisR]

Er no it's not just the area.
Look up the Box equation.
iirc flow is proportional to the diameter to the power 2.5, so the biggun will pass 5.6 times as much as the littlun.

The reason is to do with the resistance of the sides. I expect the rule changes with really big pipes.

Just googled - and reminded myself it gets horribly complicated very quickly!

 

[namsag]

Was tying to keep it simple chris , bad enough trying to get spelling right after a good afternoon session with out doing formula`s

 

[breezer]

thanks both