Effects of temperature changes on emitter discharge

Working on the assumption that temperature affects water viscosity and emit ter geometry, the writers have developed a dimensional analysis approach to the potential pressure-discharge relationship to estimate discharge sensit ivity to temperature. Its accuracy was validated by experimental data. Flow rates were measured under controlled conditions on samples of six commerci al emitters. Pressures of 100, 150, and 200 kPa were applied. Water tempera ture was modified alternating heating-cooling temperatures from 20 to 40 de grees C. A factorial analysis of variance was performed on the observed dat a with the results presented as coefficients of variation. Emitter discharg e was found to be insensitive to the alteration of heating-cooling temperat ures. Discharge of the helical long-path emitter increased with increasing temperature at a maximum rate of 0.7%/degrees C. In contrast, it decreased in the vortex emitter at a maximum rate of 0.4%/degrees C. The dependence o f orifice-type emitter discharge on temperature was less significant. Disch arge of compensating emitters was affected as much by the operating time of each test as by the time elapsed between consecutive tests, and was not de pendent on temperature change.