I work in a large water treatment facility. Chlorine is added after ozone quench/depletion. Periodically chlorine feed is disrupted. The disruption is characterized by instant loss of vacuum to chlorinator. The loss of vacuum is instantaneous and system immediately starts to recharge vacuum in pipe between chlorinator and ejector. Full recharge takes several minutes because distance between chlorinator and ejector is excessive (1/2 mile X 4 in. line). The event first causes a loss of residual then bounces high when feed is reestablished. This event may then become cyclic with a recurrence in 10 to 15 minute cycle. Although this does happen in warm months it is more frequent in cold water months. Vacuum readings on this pipe are observed to range to 23 in/Hg, (no SCADA record for that parameter). There is an approximate 30 psi drop across the ejector with 1 inch orifice. I believe that the flow across the ejector is too high. Is it possible that the ejector could continually accumulate vacuum in long line between chlorinator and ejector and reach a point where vapor pressure of water and vacuum vaporizes liquid and expansion instantly quenches production of vacuum in ejector ? We intend to measure flow with ultrasonic flow meter to verify flows across ejector.
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