Session: Research Posters

Paper Number: 173959

Measurement of Pressure Losses in Elbows of Cpvc, Pex, and Copper 

Plumbing design in residential and commercial buildings still relies on pressure loss data measured in the early 20th century, even though there have been significant advances in pipe materials and fitting designs. As modern plumbing systems begin to use plastic materials like CPVC and PEX, there is a pressing need for updated pressure loss data to allow for approaches that improve both water efficiency and quality. An accurate prediction of pressure loss through plumbing fittings is needed not only for correct pipe sizing, but also for keeping consistent pressure at fixtures and minimizing unnecessary energy use. In this study, we investigated the pressure loss across three commonly used ¾-inch elbow fittings (one each made of CPVC, PEX, and copper). A custom test rig was used to measure static pressures upstream and downstream of each fitting across a range of flow velocities (1.0 ft/s to 10.0 ft/s), from which the pressure loss coefficient was derived. This test rig consisted of pressure sensors placed before and after the fitting, connected to a data acquisition system, and designed to minimize external interference so that pressure changes could be dictated solely by the fitting that is being tested. To create a baseline for comparison for the elbows, pressure loss was also measured across straight sections of the same materials. From the data of the straight sections, we found that PEX has the highest friction factor overall, closely followed by CPVC and then copper being significantly less than both. We also found a trend for the pressure loss coefficient decreasing as the Reynolds number (Re) increases, leveling off around an Re of 40000. These trends were consistent across the straight sections and aligned with the expected fluid behavior in turbulent flow based on the Colebrook equation. We are currently in the middle of testing the elbow fittings and expect to complete this section of the study in the next few weeks. While the data collection is still in progress, we expect to observe similar trends to those found in the straight sections as well as those found in previous studies on pressure losses in elbow fittings. Once this data collection is completed, this testing will allow us to calculate friction factors and estimate surface roughness for each elbow material. These results will contribute to a more accurate understanding of how different materials and shapes affect performance in plumbing systems. By improving pressure loss modeling at the fitting level, this research supports more efficient system designs, potentially reducing construction costs, improving fixture performance, and conserving water in newly built homes.

Presenting Author: Henry Gagliardi University of Maryland, College Park

Presenting Author Biography: Henry is a M.S. student at the University of Maryland. He received his undergraduate degree from the Rochester Institute of Technology in 2022 after which he worked for Texas Instruments as a ceramic packaging engineer for their Digital Micromirror Devices (DMDs).

Authors:

Victor Mathias University of Maryland, College Park
Henry Gagliardi University of Maryland, College Park
Natascha Milesi Ferretti National Institute of Standards and Technology
Glen Glaeser National Institute of Standards and Technology
Lingnan Lin University of Maryland, College Park