Bulkhead flowrate

[sal t. nutz]

Does anyone know the exact flowrate on and internal overflow with a 1 inch bulkhead? I know the external overflow boxes are rated, but I can't help but think that an internal bulkhead of the same diameter would have a greater flowrate due to the U tube on the external. Anyway, I don't want that to be an argument, I just want to know the flowrate of an internal 1 inch bulkhead.

 

[rockface]

The only thing I could add would be when I had my tank built at a local shop they had a tank set up 300 gal with an internal mounted 1 inch overflow with a flow meter hooked up to the hose with a mag 18 return pump @ 5 feet of head that was flowing at 1100 gal per hour. I have two 1 inch overflows that drop strait into my wet dry with two mag 12, return pumps and the system is running very well. hope this helps.

 

[sal t. nutz]

Rock,
That pump didn't have a ball valve or anything slowing the flow? So I can assume that a 1 inch bulkhead can handle at least 1000gph?

 

[rockface]

no valve, just clear hose with a small black flow meter inline.

 

[surfnturf]

It all depends on the drop from the bulkhead to the sump, if you double the height differential, you wouldn't exactly double the flow, but you would increase it. Also the diameter of the plumbing from the bulkhead to the sump plays a role, a lot of variables, and you can use them all to your advantage if you think about them.

 

[almarktool]

i contacted ocinaic in regards to this and i was advised that they are good for 1000 GPH , how ever this would be prob with excellant drains, i just set up my 200 RR and i have 2 iwaki 55rlt pressure rated pumps that push 1050 gph, and the over flows could not keep up, i then did a couple changes elminated 1 elbow on each drain line and i managed to barley keep up with them running full blast, i also have 2 more elbows in each drain whiich i am looking to replace each elbow with 2 45degreed fittings for slightly better flow
when u get up there that close it gets tricky,
on the other hand i have a mag 12 pump in my 72 that has 1 overflow and there is no prob what so over i could prob run a mag 18 with no prob so part of it will depend on the quality of the pump and if it is a pressure rated pump or flow rated pump

 

[broomer5]

Sal T. Nutz
As everyone's mentioned - you'll have a tough time getting a firm answer on your question
I just want to know the flowrate of an internal 1 inch bulkhead.
There are formulas to calculate this value, but you need to know everything about the installation, piping, saltwater, distances, heights, turns/elbow radii, density of liquid or specific gravity, temperature of water, head pressures, height of water entering the overflow, slope of the drain piping, and the list goes on and on.
Tricky for sure - that's why most folks use a rule of thumb - such as 700 gph on average for a 1" pvc pipe running vertical to a sump.
But the actual flowrate is affected by so many factors - it's very hard to predict here with any certainty.
If you're still wanting more info - do a search on the internet for
"Hazen-Williams Formula" or look for fluid dynamics calculations for gravity flows.
Or do what the rest of us often do - trial and error and make some changes.

 

[sal t. nutz]

Let me explain my situation as short as I can, and maybe that will help. My 300 has 2 large trapazoid overflows. I am not worried about them handling the flow since they are big and 3 sided. In one of the overflow there is 2 1" bulkheads. In the other overflow, there is only 1 1" bulkhead (don't ask why, I bought the tank used). The 2 bulkheads are evenly spaced and look correct, in the overflow with the 1 bulkhead, it is dead in the middle, which means if I put annother bulkhead in it, it will be off-center. I know that should be no big deal, but it looks kinda sketchy to drill it. So I figured if 2 1" bulkheads could handle my return rate of 1500gph, I would just use that 2nd bulkhead in the other overflow as a dry chamber for electrical. But if they won't handle the flow, I will have to drill and run 4 bulkheads in 2 overflows, which I would like to avoid if possible. If any of this isn't clear, I can probably take pictures and post them. Thanks so much for the help so far.

 

[sal t. nutz]

Here are pics. Try not to pay attention to how bad it looks, like I said in my sig, it is getting a makeover.
Front of overflow 1

Looking in the top of overflow 1

Looking at the underside of Overflow 1

Front of Overflow 2

Looking top down on overflow 2

Underside of overflow 2

On the underside pics, if you look closely, you can see the edge of the overflow box itself, and it will help you understand where I can drill.

 

[almarktool]

hmm well i would add 3/4" bulkhead in the chamber that only has 1 and then i would open up the other 2 1" ( 1 on each end ) to accept a 1 1/4 or a 1 1/2 it should be easy to open them

 

[sal t. nutz]

Alamark you need to read my previous post where I described what i want to do. I want to avoid drilling if possible.
Golfish, yes I need 1500 gph. It's an Iwaki MD70RLT

 

[sal t. nutz]

Even with the Durso mod? Or does that even slow the flow at all?