Hello. I am trying to model out a potential application in Node-RED whereby I gradually reduce the speed of a pump that is filling a tank, so that the flowrate gradually decreases as the tank fills up. Think of slowing down the flow of water from the pump when filling up a fishtank as it starts to reach the maximum level, so as to avoid overfilling.
In my mockup, I assumed a 750 liter tank and a pump that flows at 10 liters/min. The pump runs at full flow rate up to the point where the tank is filled to 250 liters. I set up a switch node to decrease the pump flow rate as the tank is filled more and more. I have the fill_level set as a flow.context, which is used by the switch node.
The attached flow works fine, but the switch node uses static ranges for the tank fill_level (e.g. <250, 251-400, 401-550, etc.). I would like to do the same general switch node, but using percentages, i.e. if tank is 50% full, then send to output 2; if tank is 75% full, then send to output 3; etc. But I do not see any obvious options in the switch node settings for how this can be done. Any hints or suggestions are appreciated. I have a feeling that a JSONata expression can achieve this.
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