1" PVC Flow Rate?

[garyfri]

Gary, if you increase the size of the bulkhead and ALL the pipe in the drain to 1 1/2" it will flow 1500 gph vs 960 gph with a 1" pipe.

If you increase the drain to 1 1/2" pipe but still have a 1" section of pipe or bulkhead or union, then the entire system will run at the 1" diameter flow rate of 960 gph. The only way you can get more flow through a 1" pipe is to apply pressure. If the drain were in the very bottom of the tank with 2' of water pressing down on it, it would flow a little faster (the water pressure behind the weir/overflow on even a bulkhead at the very bottom would be small. The other way is to use a pump, which is impractical when trying to get water from the tank to a sump... not impossible, but I don't know anybody who does it.

Does that help?

Thank you. When you mean apply pressure can that be consider in the siphon as I assume it increase the flow as it is being pulled by the siphon correct?

 

[garyfri]

That is my thinking but this chart gets quoted here all the time.

with 2gh then does the cross-section not matter (i.e. pipe diameter). or not the velocity but the amount?

 

[garyfri]

@KStatefan and @Ron Reefman . Would the pressure required to keep the siphon of the main drain be increased as now the diameter has been increased (after the 1" bulkhead to 1.5 pipe). which would then reduce the amount of water trickling in the second drain of the bean animal. Or is this not how it works? Thank you both in advance with all the knowledge.

 

[KStatefan]

with 2gh then does the cross-section not matter (i.e. pipe diameter). or not the velocity but the amount?

Yes the cross sectional will matter. The velocity time the area will give your volume

 

[Ron Reefman]

The 'pressure' in a gravity fed system is just the weight of the water directly above the intake. There is no extra pressure to keep a siphon system running. It's having enough flow into the area behind the weir to keep the intake covered with water. That's why a small hole in the return line into the DT will break the siphon when the power goes off and the return pump shuts down. A siphon starts up, but is broken when the water level in the DT falls enough to expose the small hole to the air.