Formulating vent space for enclosed leaf box?

Discussion in 'Lawn Mowing' started by walker-talker, Jan 15, 2005.

  1. walker-talker

    walker-talker LawnSite Platinum Member
    from Midwest
    Posts: 4,771

    Ok...in another thread I was told the CFM's on my leaf loader is between 2100 to 2200 CFM's. The leafbox is 22.5 cubic yards. Anybody know the formula for calculating the necessary vent space needed?

    Thanks
    Matt
     
  2. mtdman

    mtdman LawnSite Gold Member
    Posts: 3,137

    There's a formula? I just cut some holes in the side and threw screen over it. The lco that works outta my same storage area has no vents. He has a mesh tarp over the top and the air vents outta that.
     
  3. walker-talker

    walker-talker LawnSite Platinum Member
    from Midwest
    Posts: 4,771

    Yea...I have mesh tarp now and it vents well, but just hate getting caught in the rain...weight truck down more with all that water and cost more at the dumping site.

    I am sure there has to be a formula to have adequate ventilation. I don't know what would happen if there was not enough ventilation, but I am guessing that the loader would not discharge like it's suppose to. Wouldn't it restrict the amount of air that could escape and ultimately cause air to be forced back into the discharge tube...just guessing. Do you have any pics of your setup MTD...I think I have seen it, but don't remember your vents.
     
  4. Kelly's Landscaping

    Kelly's Landscaping LawnSite Platinum Member
    Posts: 4,401

    This is one of those things you don't even think on till you realize your vent is way undersized. My first day with the leaf box we have a 20 hp giant vac that puts out 4200 cfms it nearly blew the box to pieces. It was bending 3/4 in plywood like it was not even there the back was so bad it was causing the door to deform and creating a giant hole on the edge which got so big you could almost crawl through it. I had to have one guy sit on the roof with his leg wrapped in sweatshirts to keep his leg there to block the hole the best he could. When the vacuum went on it would kick him 6 inches into the air which is not good when your 10 feet up all ready and on the edge of the box.

    As soon as we got home we made plans for and cut a much larger second vent this one being 4 ft by 30 inches the other was like 2 feet by 3 feet. I do not know the formula for vent size but when I calculated the air volume I found that the vac was filling the box when empty once every 6 seconds so that is a lot of air that needs to get out. Trial and era you will know if your vents are not big enough very quickly took me less then 2 mins to figure that one out.
     
  5. jpmako

    jpmako LawnSite Senior Member
    Posts: 593

    How about just throwing a blue tarp over the mesh tarp when it rains?
    Seems like that would just be easier than making a semi-permanent box with all the hinges and extra weight and maintenance of the plywood and such.

    Just my 2 cents

    Jason
     
  6. mowin at the lake

    mowin at the lake LawnSite Member
    Posts: 218

    The vent on my leaf trailer is 2' x 4' and is a peice of expanded metal. I might have a picture if you need.The size of the trailer is 6' wide 6'foot tall16 long.
     

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