simple HGL calculation

[elizasue1]

I have been tasked to develop a worksheet to calculate HGL. My pipeline will be a single pipeline from a pressure tank and well to a water storage tank (maybe uphill or downhill from well). The pipeline may be designed with one reduction in pipe diameter (2" Sch40 to 1.5" Sch 40). Fluids is not may strong suit, so if someone can point me in the right direction to compute HGL for a simple linear pipe system in worksheet form, I would greatly appreciate it. Challenging topic for me since fluids coursework was many years ago. I have already been to the Imnoeng site.

 

[cr1973]

HGL as I take it is simply the difference between the two elevations, as well the difference between the two pressure heads (converted to feet if elevation is in feet).

Suppose pressure tank is at elevation 100 ft, at 100 psi. That grade point is 331 feet. Assume pressure at storage tank is 80 psi, at 120 ft elevation, making that grade point at 305 feet. Now draw the line between.

 

[beej67]

The HGL is the level to which water would rise if you stuck a piezometer at any given spot in your system.

Grab an old fluids text book and look for the "energy equation" solved in terms of head, so each term is in feet. Then read five pages back and five pages forward. Should be pretty easy to figure out from there.

Basically, the HGL is part elevation head (elevation of the well, or pipe, or destination) and part pressure head. (which is the feet of water it would take to create that pressure) If there's no flow, the HGL is flat. If you know a flow rate, then you can figure out a velocity in your pipe section, then you can figure out what the friction loss will be in the pipes, which can be put in terms of head loss per linear foot. That'll be the slope of your HGL. It will be steeper for the smaller pipe. You might also have a junction loss for the pipe contraction or expansion, which will be a little divot in the HGL.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[gbam]

look for the chezy equation for losses etc... or the hardy cross method to compute head losses.

 

[jgailla]

If it's just one pipe and it's water, Hazen-Williams is probably the simplest way to calculate the head losses. The reducer and any other fittings and valves can be converted into an equivalent length of pipe using any of several common graphs.
beej67 is spot on as usual.

 

[stanier]

Download this software and you can plot HGL vs Length

http://www.pumpsystemsmatter.org/content_detail.aspx?id=110

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[bimr]

Attached is sketch of what your profile will look like.