Inflow or Outflow rate knowing volume of Cylinder Tank

I'm trying to find the formula for the inflow rate or outflow rate of a cylinder tank knowing the Volume.
Looked online and did not find much literature. Flowrate units should be Gal/Min.

Volume = pie x radius 2 x height

If you know the height of the tank then, sample it every minute to determine the Gal/Min.

Once per second, calculate tank volume in cubic inches using the formula: cubic inches = Pi * radius * radius * height. Then convert the cubic inches to gallons using the formula: gallons = cubic inches / 231.

Store the result and find the difference between it and the stored result from your prior sample.

Multiply the difference by 60 to convert GPS to GPM.

@Bit_Bucket_07 would not the result be the same as gclshortt method. Same difference.

V1-V2 =is positive then I lost volume.
V1-V2 =is negative I gained volume.

V1 being the height when sample taken.
V2 being the height after a min.

RRoc said:

@Bit_Bucket_07 would not the result be the same as gclshortt method. Same difference.

V1-V2 =is positive then I lost volume.
V1-V2 =is negative I gained volume.

V1 being the height when sample taken.
V2 being the height after a min.

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Sure. You could sample once per minute, rather than once per second, if you don't need fast updates of your flow rate. Then you wouldn't need to multiply by 60 to convert from GPS to GPM.

Knowing the level doesn't provide the inflow and outflow. The rate of change in level will provide the net difference between inflow and outflow but not the absolute value of either.

Is the flow only in or only out at any given time? If both simultaneously you have a problem, as Peter points out.

What exactly are you trying to accomplish?

Tom Jenkins said:

Is the flow only in or only out at any given time? If both simultaneously you have a problem, as Peter points out.

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True enough. I assumed that everyone (including the OP) understood that the level in the tank would never change so long as input flow is equal to output flow.

@Peter Nachtwey Understood.
@Tom Jenkins What Peter said. Trying to determine flow rate. The net difference will tell if Flow increased or decreased. Main concern is outflow data.

Based on the info provided and reasonable but necessary assumptions you will not be able to determine flow rates except by putting flow meters on piping into and out of the tank.

@Tom Jenkins: Why won't gclshortt or Bit_Bucket_07 method work?

If my Volume is 5000 Gallons at Time 1 and my volume 1min later is 4000 Gallons at Time 2.
Is not my Out flow rate 1000 GPM at Time 2?

RRoc said:

@Tom Jenkins: Why won't gclshortt or Bit_Bucket_07 method work?

If my Volume is 5000 Gallons at Time 1 and my volume 1min later is 4000 Gallons at Time 2.
Is not my Out flow rate 1000 GPM at Time 2?

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True ONLY if the flow into the tank is zero during that minute. This is why I asked if flow was just in or just out in a previous post. You have not answered that question. The two posts cited are predicated on flow in one direction only and are essentially showing how to calculate the volume.

There is a method for calculating flow out of a tank with continuous flow into it, based on volume changes. It only works if you can stop flow out of the tank for a measurable period of time. An example is attached.

RRoc said:

If my Volume is 5000 Gallons at Time 1 and my volume 1min later is 4000 Gallons at Time 2.
Is not my Out flow rate 1000 GPM at Time 2?

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That would depend on the inflow.

What if the inflow was 2000 GPM during that minute. What would the outflow have to be to give you a volume of 4000 gallons at the end of the minute.

If my Volume is 5000 Gallons at Time 1 and my volume 1min later is 4000 Gallons at Time 2.
Is not my Out flow rate 1000 GPM at Time 2?

Click to expand...

If your intent is to measure the change in the tank's contents, then yes, that's 1000 GPM. It is not the flow rate in the outflow pipe unless there is no flow in the inflow pipe.

Here's an example to show why the distinction matters. Suppose your tank processes some material. You are paid $2 per gallon for what comes out of the tank and you pay $1 per gallon for what comes in. Based on your calculation you're making $2000 per minute. Sounds good.
But what if the flow in is 2000 GPM and the flow out is 3000 GPM? Still a net difference of 1000 GPM, but you should actually have revenue of $6000 per minute and cost of $2000 per minute for a net of $4000 per minute.
It's even worse when the tank's content is increasing. At 2000 GPM out and 3000 GPM in there is a net difference of 1000 GPM into the tank. Based on your calculation that's costing you $1000 per minute. Based on what's actually happening, you should still be making $1000 per minute (($2 * 2000 GPM) -($1 * 3000 GPM)).

@Tom Jenkins Thank you. Greatly Appreciated.