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Thread: DC Ducting

  1. #1
    Join Date
    Jan 2011
    Location
    Northern UT
    Posts
    762

    DC Ducting

    Working on the ducts for my shop. Just installed a CV1800 with the 16" impeller. Question is, for the vertical drops, am I better doing 45 degree turns down, with a section of 6" metal pipe, then using a perhaps 24" long or so, section of flex tubing? Or just do a 90 degree turn with a straight pipe connected by a very short piece of flex pipe? Basically does the longer length flex pipe outweigh the better 45 degree turn?

    Any other suggestions or 'rules' would be much appreciated.
    I am in love with Montana. For other states I have admiration, respect, recognition, even some affection, but with Montana it is love.... It seems to me that Montana is a great splash of grandeur....the mountains are the kind I would create if mountains were ever put on my agenda. Montana seems to me to be what a small boy would think Texas is like from hearing Texans. Montana has a spell on me. It is grandeur and warmth. Of all the states it is my favorite and my love.

    John Steinbeck


  2. #2
    Join Date
    Apr 2017
    Location
    Bucks County, PA
    Posts
    198
    Start here: https://airhand.com/designing/


    basically, you need to determine the ‘equivalent length of straight pipe’ for the 24” of flex + 45 deg el -vs- the 90 deg el to see which combo has the lower resistance.

  3. #3
    Join Date
    Apr 2006
    Location
    Phoenix AZ Area
    Posts
    2,505
    One 90 degree elbow is equal to 6 ft of straight pipe. One 45 is equal to 3 feet of straight pipe. Two 45s would be the same as one 90. One foot of flex hose is equal to 3 feet of straight pipe. So 24" of flex is equal to 6 feet of straight pipe. One 90 and straight pipe would be less resistance than two 45s and flex if I understand your options correctly. Only because flex is 3X straight.

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