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Thread: Doser stopped dosing automatically

  1. #11
    Join Date
    27.05.2015
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    We provided an example of a digital scale so you can use a more precise calibration tool for calibrating...how does that not help solve the problem?
    The pump is running as commanded. The inaccuracy is a direct result of the calibration attempt.

  2. #12
    Join Date
    13.02.2020
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    124

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    Quote Originally Posted by Vinny View Post
    We provided an example of a digital scale so you can use a more precise calibration tool for calibrating...how does that not help solve the problem?
    The pump is running as commanded. The inaccuracy is a direct result of the calibration attempt.
    Firstly can I apologise? I was using my iPhone when I replied to your post and didn't even notice the link. I have now looked at that link and unfortunately, that make/model of scale is not available in the UK and I can't find anything of the supposedly same accuracy which I have to say I find it slightly difficult to believe that it can be accurate to weigh to 0.5 ml accuracy.

    I do have some similar scales(not 0.5 ml accuracy) which I have tried to use but it seems to be less accurate than the measuring cylinders etc. When calibrating dosing pumps etc most companies use/provide a measuring cylinder to calibrate and I can't recall seeing anyone advising using measuring scales. I am not suggesting that you should be providing one by the way. Even your manual says to use "A 50ml or greater graduated cylinder or beaker to measure fluid dispensed" Also your Youtube video says to use a measuring cup and/or cylinder.

    Screenshot 2020-04-02 at 13.09.29.jpg

    Having said all that I have tried all ways to get the pump to dispense an accurate 1.5 ml to no avail. I have tried speeds 0 and 1 and saved and calibrated numerous times and am getting differing dosed amounts most times which is concerning, to say the least. The closest I have got is 1.2/1.3 ml dosed at 0 speed and calibrated at 10ml per min and I guess I will have to go with that and monitor its effect on the aquarium and try and adjust from there as required. Not very satisfactory.

    I would be interested to know if anyone else is trying to dose a similar amount of 0.5 ml accuracy and what results they are getting.

  3. #13
    Join Date
    27.05.2015
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    No worries.

    If you're asking the doser to dispense 1.5ml and it gives you 1.3ml, that is within the acceptable tolerances of the motor, +/- 0.2ml.
    In most cases a graduated cylinder is OK to use when you're dosing much larger amounts like. Remember, that video has to accommodate most cases which means it is a general video covering calibration. It is not specific to those wanting to dose such small amounts to the tenth place, that is when the digital scale becomes more useful.

  4. #14
    Join Date
    13.02.2020
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    124

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    I have not seen anywhere about the +/- 0.2ml but if that's the case fair enough.

    All I have seen on the website is "The 24V stepper motors allow precise dosing even at the smallest flow rates (0.1 ml)." and "Conveying capacity and dosing:8-45 ml/minute (precisely adjustable to 0.1 ml)"

    It might worth some clarification on this point if what you are saying is the case.

    When I acquired the doser I was not necessarily expecting such accuracy but based on what is indicated in the literature it leads you to believe that it can maintain accuracy of 0.1 ml

    Many thanks

  5. #15
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    13.02.2020
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    @Vinny after many calibrations this problem now seems to have settled down and dosing 1.5 ml Using Speed 0 and 4ml flow rate.
    Thanks now just waiting for the arrival of a P4E and KH Director.
    Hopefully, I will get my mind around these more smoothly
    Last edited by mlandscape; 16.04.2020 at 11:01.

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