A bit of background on flow meters: Flow meters do not output a tacho signal, they output pulses. Flow meters do not notify the connected controller when flow has ended for good, i.e. they don’t tell it ‘This was the last pulse; we are at 0 ml/s’. The controller’s firmware can never be sure whether another pulse is going to come or not. But it has to calculate the flow anyway. Therefore, the firmware has to make an educated guess as to when 0ml/s has been reached and flow has ended. It cannot output the flow rate calculated with the previous pulse endlessly. leva! uses a 1.5s timeout: If no new pulse is received within the next 1.5 seconds, it is assumed that the flow has ended and 0ml/s is calculated. The Status Monitor can then draw a line from the last mesurement, 1.5s ago, to 0ml/s at present time (using a larger timeout would make the end of shots look weird in the Status Monitor, so that is not a good option). At 0.5ml/s, an FHKSC generates one pulse per second. The timeout will not be triggered. At 0.3 ml/s, there will be 1.7 seconds between pulses. The timeout will be triggered and 0ml/s will be calculated. You complain that flow meters are “quite inaccurate under 1 ml/s” but your scale plot suggests that you have only 0.3 ml/s, not 1 ml/s. I find flow meters quite accurate at 1ml/s and they work down to 0,5ml/s. I don’t think measuring rates such as 0.3 ml/s is of importance but if it is to you: When you configure ito, you can choose between the Digmesa FHKSC and the Digmesa nano series. The nano series generates 20 times more pulses than the FHKSC series.
