Need help in designing a mixed coolant dispenser
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  1. #1
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    Default Need help in designing a mixed coolant dispenser

    Hello guys, I have a query regarding which method of inline mixing of a coolant with water would yield a homogeneous mixture. Application is to mix a coolant with water at a particular concentration possibly without using an agitator or a separate tank.

    Coolant is fed from a drum using a pump and water is fed under gravity. Both liquids are mixed in-line in a dispenser (static mixer.. or just in a pipe) and fed to the machine sump.

    Case 1 : Both liquids turn on at the same time. Since coolant quantity is very less compared to the quantity of water (1:20 approx), required coolant flows out of the dispenser before the required water. The two liquids might mix in the sump.

    Case 2: I 'pulse' the coolant.. for eg. if I have to feed 5 litres of coolant concentrate with 95 litres of water, i divide the flow time of coolant into 10 equal pulses.. i.e 500 ml per 9.5 litres of water. The coolant pump turns off after every 500ml of coolant passes through, and turns ON after 9.5 litres of water has flown. And so on...

    Case 3: I use proportional valves & variable flow-rate pumps to match the flow-rate of chemical and water so they start and stop at the same time. This increases the capital cost multi-folds due to the use of the proportional valves and the special pump.

    Which one would you recommend?

    I have taken a small lab-scale trial but could not really find too much of a difference in the concentration of the mixed solution in each case. I am interested in achieving a homogeneous mixture before the solution reaches the sump, and not rely on agitation in the sump to cause the mixing.

    I am not convinced by Venturi mixers as they require a constant flowrate and pressure of the 'motive' fluid (water). Dosatron units don't allow automatic changing of mixing ratios, otherwise they would have been ideal.

    Also, would you guys happen to know of the Auto Refill option on Haas machines? I know it uses a Venturi mixer, but would like to know if it is effective like it claims.

    Any help will be appreciated. Thanks.

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    Maybe you are making a mountain out of a molehill or maybe not.
    Added fill should not be done at a fixed "new" mix.

    Water in the machine evaporates much faster than coolant. Hence the need to check the sump concentration and change the mix of what goes in.
    Sometimes all you need is 100% water.
    Adding a fixed xx% will end up with way too high a coolant concentration over time for me.
    Auto plants audit this on a weekly or less basis and you get a e-mail from the lab to add xx volume of coolant to a specific machine or shared sump.
    Then there are coolant additives if only one part of the coolant is out......

    First off is testing of what is in the sump and adjusting mixing from there. If not doing this you are running blind and all this nifty tech means nothing.
    Bob

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    There is definitely a simple solution to this. At my work we have a valve on the concentrate drum. Water in, and mixed solution out. The water moving through the valve pulls the oil up out of the drum on the way through with a handle to adjust the concentration. Couldn't tell you what it's called but could ask around on Monday if no one else steps in who knows what I'm talking about. It screws onto the drum with a tube to draw from the bottom.

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    Quote Originally Posted by CarbideBob View Post
    Maybe you are making a mountain out of a molehill or maybe not.
    Added fill should not be done at a fixed "new" mix.

    Water in the machine evaporates much faster than coolant. Hence the need to check the sump concentration and change the mix of what goes in.
    Sometimes all you need is 100% water.
    Adding a fixed xx% will end up with way too high a coolant concentration over time for me.
    Auto plants audit this on a weekly or less basis and you get a e-mail from the lab to add xx volume of coolant to a specific machine or shared sump.
    Then there are coolant additives if only one part of the coolant is out......

    First off is testing of what is in the sump and adjusting mixing from there. If not doing this you are running blind and all this nifty tech means nothing.
    Bob
    Bob, I feel like I should have explained my application better. The increase in concentration due to evaporation has been considered by us. We will be adjusting the top-up concentration after checking the coolant level in the sump. Rest assured we will not be adding the same concentration everytime as that will definitely take the coolant concentration to insanely high levels.

    Regarding adding 100% water, our experience and even our coolant supplier has advised mixing a small (0.5-1.5%) of coolant in the top-up mixture to not disturb the emulsion in the sump. Hence the requirement for this equipment.

    Apologies for not clarifying every detail in the original post.

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    Quote Originally Posted by Nagol View Post
    There is definitely a simple solution to this. At my work we have a valve on the concentrate drum. Water in, and mixed solution out. The water moving through the valve pulls the oil up out of the drum on the way through with a handle to adjust the concentration. Couldn't tell you what it's called but could ask around on Monday if no one else steps in who knows what I'm talking about. It screws onto the drum with a tube to draw from the bottom.
    @Nagol, this is the venturi mixer that i have described in the original post. Our company has a couple of these, but they always produce different concentrations due to variation in the water pressure.

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    just use a venturi metering system.
    We just turn the water tap on and it draws concentrated coolant into the water stream at a set rate.
    Its as easy as turning on the tap.

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    Add a pressure regulator to the water upstream of the venturi mixer. Make sure it is set to some pressure less then the lowest city water pressure it will see.
    Would one of those bar drink miking machines work. I have no idea how they work. probably a lot of used ones out there as bars and restaurants close due to covid.
    Bil lD


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