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# Gravity Flow Line Sizing Calculation

gravity gravity flow line sizing

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### #1 samayaraj

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Posted 23 February 2014 - 05:26 AM

Dear all,

Here I've attached the excel sheet for calculating the line size for gravity flow. This excel I've prepared to calculate the line size for DM water transfer from overhead storage tank to condenser. I used the basic hydraulic calculation for this. In this excel, I've data base for pipe and pipe sch data and quick drop down list to select the size and sch and options to select MOC of pipe.

With the selected pipe size, we can check whether the pipe is suitable or not. If suitable, how much pressure to be reduced in control valve also provided.

Kindly enable MACROS before using this excel.

Regards,

Samayaraj

#### Attached Files

Edited by samayaraj, 23 February 2014 - 05:31 AM.

### #2 Ajay S. Satpute

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Posted 24 February 2014 - 01:20 AM

Samayaraj,

The excel sheet is indeed very impressive. It could have been even better, if formulae, codes etc. were not password protected.

Regards.

Ajay S. Satpute

### #3 Art Montemayor

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Posted 24 February 2014 - 09:04 AM

If the calculation sheet is designed for calculating gravity flow, then it is not shown appropriately.  The depicted sketch is not one for gravity flow.  It is driven by a pressure driving force between both vessels.  In order to have a gravity flow effect, both vessels must exist at the same pressure and an equalization line is needed between the top of both vessels for that to occur.

• Is the Darcy equation used to account for the frictional loss in the pipe and fittings?  We can’t see the algorithm or logic employed to decide on the proper diameter to conform to the available pressure drop.
• The difference in friction factors between stainless steel and carbon steel is not practically perceptible in practice.
• Use of the Churchill friction factor equation would be faster and more direct than the Colebrook equation.
• The calculation sheet is cut off on the right hand side.  There is no column for the pipe fittings and pipe schedule No.

### #4 Bobby Strain

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Posted 24 February 2014 - 03:39 PM

If you want anyone to make use of your work, you need to stop hiding the code. And I won't repeat this suggestion again.

Bobby

### #5 samayaraj

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Posted 25 February 2014 - 01:41 PM

@ Mr. Ajay & Mr. Bobby: I am posting my excel to get used by our forum members. So, I've removed the password and I've protected the sheet without password. This is to avoid if we delete/ change the parameters by mistake. Kindly look at it.

@ Mr. Art: I agree you comment. I've read your post regarding gravity flow in our forum. If both the vessels are in same pressure, it need to be vented or an equalizing line with proper line size to be provided. I will do a separate excel sheet for this. But with this excel, by assuming both the vessels are vented/ equalized properly and we can do the line sizing.

I've removed the password and made the back calculation sheet visible to check the logic I've used. Kindly look at it. I've used darcy equation to find the pressure drop. There is a column for pipe size and sch no. selection. May be, I've removed the horizontal scroll bar. Because of that, you may not be able to see it. Kindly look at the attached excel, where I've included horizontal scroll bar, formula bar etc.

Since I'm using "goal seek" option to find the friction factor, colebrooke & white equation I felt easy to use. In my upcoming excel, I will use churchill equation.

Regards,

Samayaraj

#### Attached Files

Edited by samayaraj, 25 February 2014 - 01:42 PM.

### #6 Bobby Strain

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Posted 25 February 2014 - 04:37 PM

Samayaraj,

Thank you for your open sharing. We all work best in this manner. And, now, you will undoubtedly get some good comments and suggestions.

Bobby