Unloading fly ash

Discussion in 'Tanker, Bulk and Dump Trucking Forum' started by auto293, Jun 23, 2021.

  1. auto293

    auto293 Bobtail Member

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    So I've got a question I'm only on my 5th fly ash load and it seems like it's taking forever to unload is there any tips? I'm using no top air only the aerators but I'm loosing pressure in the line so I'm only unloading at 8 when I should be unloading at 10 or 12
     
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  3. Roberts450

    Roberts450 Road Train Member

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    Product valve fully open? I haven’t done fly ash but have done boiler ash, hydrated lime, but mostly flour. Most products I run the product valve fully open then vary the mainline (mixing) valve to adjust the tank/line pressure to the products liking for a smooth but fast unload. So if you’re running low on pressure close off the mainline valve a couple notches forcing more air through the aerators, give the trailer 5-10 minutes to adjust to the new airflow. Small adjustments tell you find her happy spot then let the trailer do its thing tell you’re empty.
     
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  4. RockinChair

    RockinChair Road Train Member

    Have you checked to make sure that your dome lid gaskets and product valve gaskets aren't leaking?

    What pressure are you building the tank up to before you start unloading? Tank pressure will drop a little bit once you start, but if it's getting too low just close the discharge line valve little bit so that way it'll send more air through the aerators into the tank.

    You only need enough air in the discharge line to keep from plugging up.
     
  5. s0231198

    s0231198 Light Load Member

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    A lot of places I go and unload flyash, I usually run the air open a notch or 2 and sometimes I don't even open it and always have the product valve open fully with it to keep pressure in the tank, bc it doesn't take much air to move flyash through the hose. The more air you put into the line from your air assist valve the slower it actually unloads it bc it's pushing the air through the product and not pushing the product.
     
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  6. auto293

    auto293 Bobtail Member

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    I am building up to 12 lbs and I close my top air and open proportion valve all the way open and open the product
     
  7. auto293

    auto293 Bobtail Member

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    Dec 10, 2019
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    So I build pressure at 12 close my top air open my proportion valve which I'm guessing is the air assist? And open the product so I don't need to open the proportion valve all the way open to push product through the line?
     
  8. auto293

    auto293 Bobtail Member

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    Dec 10, 2019
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    This is what my trailer looks like
     

    Attached Files:

  9. Roberts450

    Roberts450 Road Train Member

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  10. s0231198

    s0231198 Light Load Member

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    I have done it both ways, either with the aerator valve open (Mine does not have individual valves on each aerator line), and also with the top air open just to see if had any difference, when I had the time to try some things different just to see what would happen, and it was about the same time frame, but it only worked for flyash since it kind of flows on its own. Most powders you have to use the aerators on them, as they will pack in and not fall out product valve, hence the reason for aerators on bulk trailers. There is some products I know for sure of, and I know there are others, that you do not want the aerators open at all or you will have a huge chunk of product form in tank, examples being sugar and plastic pellets bc they will heat and melt together.

    The easiest thing I can tell you, is start it up and build your pressure, 9/10 times we open our air assist ( the valve that feeds air to your product line, which is the one behind your front fender on your MAC trailer) to about halfway open, and then slowly open product valve, and see what the pressure does, it takes a minute or 2 to stabilize from your initial pressure drop and then either open it or close it a little bit at a time. This depends a lot on the trailer as well and how well its maintained and everything, some trailers you can have air closed almost all the way to maintain pressure, and some you have to open all the way or a lot more to keep pressure down. Its a learning curve with each trailer. I almost always go back and put a foot on hose just to feel what the product is doing. You can gauge quite well after doing it a few times as to whether the product is moving through the hose, or you are just pushing air through it, or if its putting product in the hose but not moving it. Try not to make drastic changes with the air assist, unless its on the verge of plugging up and you need to get air through line, usually I go a notch or even half a notch at a time and see what it does to pressure. Sometimes going one full notch will drop your pressure quite a bit, as only doing half of one will put it right where you want it to be and stay there.

    The other thing you can play with is your blower speed, not all products require your blower to be maxed out on rpms. My truck is set for max engine rpm of 900 for blower, which I believe spins the blower at close to 3,000 rpm pushing air through it (Checked it when was new but don't remember numbers off hand), but like flyash since it'll blow the air right over it in hose, I back rpm's down to 750-800 on engine, and it slows blower down to around 2,000 rpm, bc it works better there for pushing flyash. Also the longer you have to push it horizontal it'll take a little bit longer than it going vertical.

    Also since you can shut off your aerator lines, try to always reach down while unloading that pocket and make sure the hoses are warm to touch, that way you know they are not plugged up and that they are aerating product, that will also cause pressure to drop as its not sending air to tank.

    Not sure how long you have been doing pneumatic, but it's always a learning curve with products, and different plants, so it kinda always keeps you on your toes!
     
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  11. RockinChair

    RockinChair Road Train Member

    @Roberts450 is right. As soon as the product starts flowing, cut the proportioning valve back to halfway open.

    Or, you can leave the proportioning valve all the way open and open 2 product valves.

    Either way, you need to create some resistance in the discharge line.
     
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