Net pressure loss coefficients were studied for closely spaced or close-coupled pipe ells. The test fittings were all short radius (R/D = 1) 2-in. (5.08 cm) threaded malleable iron and 4-in. (10.16 cm) forged steel weld pipe ells. The ells were tested in the four close-coupled pipe configurations of a U shape of two ells in plane, a Z shape of two ells in plane, a torsional configuration of two ells out of plane, and a swing configuration of three ells out of plane. Each configuration was tested with different spacings between fittings of 0, 1, 2, 3, 4, 5, 10, and 20 pipe diameters. An additional spacing of 50 pipe diameters was tested for the Z configuration with 2-in. (5.08 cm) ells. A comparison was made between the net pressure loss coefficients of the close-coupled ells and an equal number of uncoupled ells. The comparison showed that the net losses of the close-coupled fittings were less than those of the uncoupled fittings for configurations with less than 20 pipe diameters of spacing between fittings. For the fitting spacings greater than or equal to 20 pipe diameters, there was no effect or difference between close-coupled and uncoupled pipe ells.

Units: Dual