Daily Question: Methanol and Purification Technology Forum Edition 20191024

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Regarding the question of whether to slightly open the outlet valve before starting a centrifugal pump: It is not necessary, nor is it required, to open the outlet valve before starting the pump. Because: When a centrifugal pump is first started (the situation is different when a standby pump is activated), there is no water nor pressure in the pump’s outlet pipeline, and thus no pipeline resistance. If the outlet is opened in advance, at the moment the centrifugal pump starts, it may result in an extremely high flow rate, leading to a high power output from the pump’s motor; this can easily cause overload and may damage the pump’s motor and electrical wiring. Therefore, the outlet valve must be closed at the time of startup, and it should be opened gradually after the pump has started up, so that the pump can operate properly.