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Pressure drop across "pulled" reducing tees

Pressure drop across "pulled" reducing tees

Pressure drop across "pulled" reducing tees

(OP)
Gentlemen/Ladies,

Does anyone have experience in calculating the pressure drop across a "pulled" reducing tee where the branch pipe extends inward to the feed pipe (minutely), or perhaps would the values of a "mechanical" reducing tee be adequate? In addition where would one look to find "published" pressure drop values across a reducing tees?

Seemed like a simple task to undertake, however, multiple attempts to simulate (through calculation) never yielded a similar output as derived from empirical testing (performed by outside vendor).

A plumbing manifold consisting of seven (7) - 0.460 ID copper "riser" tubes, 80.625" in length, spanning two (2) - 1.055 ID copper "header" tubes, 38.50" in length. The riser tubes are equally spaced along the center of the header tubes 4.646" between each tube.

Fluid flow across the manifold would be across opposing corners with the two remaining openings capped. See below:
       ________________________________
     [ ___  __  __  __  __  __  __  ___ --> OUT
          ||  ||  ||  ||  ||  ||  ||
          ||  ||  ||  ||  ||  ||  ||
          ||  ||  ||  ||  ||  ||  ||
          ||  ||  ||  ||  ||  ||  ||
          ||  ||  ||  ||  ||  ||  ||
       ___||__||__||__||__||__||__||___
IN --> ________________________________ ]

I stumble at the "tee" intersections. Everybody and their brother provides calculators for determining the pressure drop across a straight piece of pipe. The CDA (Copper Development Association) offers "equivalent length" values for standard tee arrangements, however, I am unable to find values for reducing tees.

My ASHRAE manual covers "same size" (inlet/outlet) conventions, but doesn't touch on reducing fittings in pipe sizing.

In any event, I am looking to calculate and/or extrapolate the numbers for additional piping configurations (increased riser lengths and quantities).
My data as derived through empirical testing is as follows.

Flow Rate: 0.0386 kg/s Pressure drop: 69 Pa (0.010 psi)
0.0631 kg/s 186 Pa (0.027 psi)
0.0946 kg/s 422 Pa (0.061 psi)

Any insght would be greatly appreciated...



RE: Pressure drop across "pulled" reducing tees

If your branch piping lips into or somehow extends into the headers, there will be additional exit or entrance losses.  Most fluids texts discuss the exit and entrance losses of nozzles with projections running into tanks, which I think IF I recall correctly can in some cases be as much as 0.65 * H (?)

If you have special header configurations, you can only be expected not to find those in the standard diagrams, so I recommend you either do some CFD, or continue with your testing program and let us know the results.

BigInchworm-born in the trenches.
http://virtualpipeline.spaces.msn.com

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