Start/stop of metering pump
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Before starting the metering pump, ensure that its stroke is at zero; after starting the motor, gradually adjust the stroke. When stopping the pump, gradually reduce its stroke to zero, and then stop the motor. What are the consequences if the stroke is not at zero before starting the pump, or if the stroke is not reduced to zero before stopping the pump?
I’ve never done it that way; it’s always on a fixed scale, and no one adjusts it when starting or stopping. If adjustments are needed, they are made while it’s in operation. It’s a very small pump that draws little current; the cables and other components used are probably on the larger side, as it’s not possible to make them any smaller.
Volume pumps maintain a minimum load when starting and stopping, thereby preventing the motor from burning out or causing power outages. In practice, these small pumps are not needed at all; the motors used for them are often quite large.
Generally, there’s nothing wrong with the motors; it’s just that the diaphragms wear out more quickly
Once the schedule is set, there’s no need to make any changes; simply start or stop the pump as required
Why does the diaphragm wear out so quickly? I need some guidance
There are many reasons: poor diaphragm quality, incorrect diaphragm material, inappropriate pump selection, and so on. You need to specify more details: what medium, temperature, viscosity, particle size, etc.; what type of diaphragm pump is being used, and what kind of diaphragm
Metering pumps are pre-set before leaving the factory, and can be used straight away
I think it doesn’t matter; the impact isn’t that great
It doesn’t have a significant impact. Adjusting the settings every time the pump is switched can affect flow control, so for diaphragm pumps, once the stroke setting is adjusted, it remains unchanged; during switching operations, manual control of the flow rate via DCS is sufficient. As for the diaphragm, I don’t think it’s prone to damage. When operating this type of pump, it’s essential to ensure that all connections before and after the pump are open during startup, and to stop the motor first before closing those connections when shutting down the pump; otherwise, pressure buildup can be harmful to the diaphragm
Personally, I think that following the operating procedures will definitely ensure no problems, but in practice, as long as the inlet and outlet are open, there will be no pressure buildup, so it’s not a big issue to start and stop the motor directly.