mitered vs smooth

ysn

Senior Member
Arabic
Hi, please what is the difference between mitered and smooth in this context:
"100 mm radius mitered 45 degree elbow equivalent length 750 mm"

"150 mm radius smooth 45 degree elbow equivalent length 300 mm"

Source: Building Code

Thank you
 
  • johnshen64

    Member
    English
    Here it means cutting both pieces at 45 degrees and putting them together. It may or may not be smooth.
     

    ysn

    Senior Member
    Arabic
    It talks about clothes dryer duct when using elbow fittings. It covers the typical short radius mitered elbows and the equivalent lengths to the various types of elbow fittings.
     

    ysn

    Senior Member
    Arabic
    johshen64, there is a table talks about dryer exhaust duct fitting type and equivalent lengths like:

    "200 mm radius smooth 90 degree elbow ...length equivalent 475 mm"
    "200 mm radius smooth 45 degree elbow...length equivalent 300 mm"
    "100 mm radius mitered 90 degree elbow ... length equivalent 1500 mm"
    "100 mm radius mitered 45 degree elbow ... length equivalent 750 mm"
    So the question is: What is the difference between smooth and mitered?
    I expect mitered means connected, in other words, fittings are connected to the elbow either by 45 or 90 degrees, but I am not sure from this meaning.
    But "smooth" here I don`t know its meaning here at all.
     

    ysn

    Senior Member
    Arabic
    TABLE
    DRYER EXHAUST DUCT FITTING EQUIVALENT LENGTH
    DRYER EXHAUST DUCT FITTING TYPE
    EQUIVALENT LENGTH
    100 mm radius mitered 45 degrees elbow
    750 mm
    100 mm radius mitered 90 degree elbow
    1500 mm
    150 mm radius smooth 45 degrees elbow
    300 mm
    150 mm radius smooth 90 degree elbow
    525 mm
    200 mm radius smooth 45 degrees elbow
    300 mm
    200 mm radius smooth 90 degree elbow
    475 mm
    250 mm radius smooth 45 degrees elbow
    225 mm
    250 mm radius smooth 90 degree elbow
    450 mm
     

    Andygc

    Senior Member
    British English
    A mitred (BE spelling) elbow turns abruptly through 45 or 90 degrees; the tubing is cut at half the angle and two pieces joined. A smooth elbow is curved to turn through 45 or 90 degrees; the tubing is bent, not cut.
     

    Andygc

    Senior Member
    British English
    Thank you very much for your best efforts.
    Do you have access to Google searches? If so, you might make a little more effort yourself. There are many images of mitered (or mitred) elbows.

    90-deg-mitered-elbow.jpg


    and of smooth elbows
    die_formed_elbow1.png
     

    ysn

    Senior Member
    Arabic
    I mean I don`t understand the words "smooth" and "mitered". There is no context to explain what "mitered" or "smooth" means.
    I understand the elbow with 90 or 45 degrees, but this does not explain the meaning of both words, mitered and smooth.
    Smooth is a very easy word, but what does it mean in comparison to "mitered"?
    I hope you get the point Andygc?
     

    Andygc

    Senior Member
    British English
    A mitre is a type of joint. There are 4 mitres in the picture of the mitred elbow above.
    There are 3 mitres in this elbow
    images
     

    ysn

    Senior Member
    Arabic
    But in the table, why do they call it elbow, not fittings?
    So "smooth" means no fitting in the elbow? which means that has a smooth surface, which is clear from anything?
     

    Edinburgher

    Senior Member
    German/English bilingual
    But in the table, why do they call it elbow, not fittings?
    We don't use the word 'fittings' for this. The elbow is the whole thing. If we look at Andy's picture in #11, the elbow consists of four sections with three joins, which are mitered joins. Mitred means they have these corners in them. This makes it possible to build the elbow using simple flat sheets of metal, rolled into cylinders and then cut at an angle.
    So "smooth" means no fitting in the elbow?
    Smooth means there are no corners in the elbow. As in the lower picture in #9. You can't make a smooth curve from joining flat sheets of metal together.
     

    Andygc

    Senior Member
    British English
    Smooth has its usual, primary, meaning:
    free from projections or unevenness of surface; not rough
    The curved pipe that forms the elbow has no bumps, creases or joints.
     

    Uncle Jack

    Senior Member
    British English
    So smooth means one curve/turning piece?
    Both types of elbow are bought as a single piece.

    A smooth elbow:
    1645874637126.png


    A mitered elbow:
    1645874655185.png


    A smooth elbow offers a lower resistance to fluid flow than a mitred elbow, and I expect that if your table of equivalent lengths listed a pair of elbows where the only difference was that one was mitered and the other was smooth, that the equivalent length of the mitered elbow would be greater.
     

    ysn

    Senior Member
    Arabic
    Of course, the table states exactly as you said, Uncle Jack, but without paying attention to resistance, just their lengths as mitered and smooth elbows.
    Thank you very much, Uncle Jack.
     

    Uncle Jack

    Senior Member
    British English
    The equivalent lengths appear to be a measure of flow resistance, hence smaller radius elbows having longer equivalent lengths than larger radius elbows.
     
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