[Anonymous]

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:
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[ ___ __ __ __ __ __ __ ____ –> OUT
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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…

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