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### Topic: Flow Calculation  (Read 2415 times)

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#### Clanouper

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##### Flow Calculation
« on: November 04, 2014, 06:05:52 AM »
Hoping someone can help.  Want to build a reservoir that will produce a consistent stream of water out of it by (i.e through holes are a slit in the bottom of reservoir.  Tank volume ~ 13 gallons; Dimensions 30x8x10 inch3.  Flow into the tank can be variable but let's assum 100 gallons / hour.  Flow rate can be adjusted.  Height of the reservoir above landing point is 12 inches. I want to estimate the quantity and amount of holes (of Area A) I can drill into the bottom of rervoir so that the tank does't overflow at a given inlet flow rate and that it has sufficent pressure to stream water out of the reservoir into a holding tank.

#### Hunter2

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##### Re: Flow Calculation
« Reply #1 on: November 05, 2014, 02:48:46 AM »
If you flow in is 100 gal/h, then the flow out should be the same. If you know the diameter of the inlet pipe . Then you need the same area for out let. Now it depends which diameter the holes will be you want to drill. The formula is diameter inlet pipe = number of holes x diameter of drilled hole.

#### curiouscat

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##### Re: Flow Calculation
« Reply #2 on: November 05, 2014, 03:07:51 AM »
If you have just a sharp edged hole my calculation says 0.4 inch dia hole would allow 100 gal/h.

So to be safe I might use a 1/2 " hole.

I'm assuming 30x8 is the cross section & 10 inch is the height? I'm also assuming you'd want the tank to run say 80% full.

Coefficient of discharge I assumed was 0.62

#### curiouscat

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##### Re: Flow Calculation
« Reply #3 on: November 05, 2014, 03:10:11 AM »
If you know the diameter of the inlet pipe . Then you need the same area for out let.

Why? I don't think that'd work.

The head isn't the same. A good pump pumping through a 2" pipe  will give you tons more flow than a 2" hole in the bottom of a 10" tall gravity drained tank.

#### Hunter2

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##### Re: Flow Calculation
« Reply #4 on: November 05, 2014, 04:10:24 AM »
Quote
Flow into the tank can be variable but let's assum 100 gallons / hour.

That is the given goal.  100 gal/hr . So inlet is equal to outlet. If les hole its overfilling, if to much hole the tank runs empty.

#### curiouscat

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##### Re: Flow Calculation
« Reply #5 on: November 05, 2014, 04:41:49 AM »
Quote
Flow into the tank can be variable but let's assum 100 gallons / hour.

That is the given goal.  100 gal/hr . So inlet is equal to outlet. If les hole its overfilling, if to much hole the tank runs empty.

Umm yes, that's why you need the right size of hole. To match the 100 gal/hr feed rate.  You punch a hole too small & the tank will overflow. Too big & it will empty.

The right hole size is unrelated to the dia of the inlet pipe.