HEAD LOSSES AND EXPERIMENTAL LOSS COEFFICIENT IN 45° AND 90° ELBOW OF PVC SMALL-DIAMETER PIPES FOR SINGLE-PHASE FLOW AND MODERATE REYNOLDS NUMBERS

This study presents head losses (hL) and loss coefficients (K) obtained experimentally for schedule 40 PVC pipe elbows, with 90° and 45° in small commercial diameters of ½ to 1½ inches that are commonly used in small networks saturated with pipe fittings. The investigation was conducted on a system constructed with short pipes that do not allow flow development, fittings necessary to measure, direct and control flow, as well as to evaluate head losses at the elbows. Simple water flow was used with rates of 0.342 to 0.980 lps (Q), which generated moderate Reynolds numbers (Re) of 13337 to 80221. It was found that hL showed dependence on the velocity head in all elbows, as well as that hL are greater as the diameter increases for the same velocity head. The K values in the elbows tended to be constant when Q > 0.75 lps, but for Q < 0.75 lps the K coefficient increased inversely proportional to Q, becoming larger as the diameter increased. Likewise, the K coefficient tended to increase as Re decreased, while K tended to be constant as Re increased. The results of the experimental coefficient were compared against the K values reported in the literature, where significant similarities and discrepancies were found.