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  #21  
Old 12-15-2016, 12:56 PM
Bradleyc1982 Bradleyc1982 is offline
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Quote:
Originally Posted by tinmetal View Post
(1.1414 xoffset) -2 (.414x (clr) centre line radius this is the formula
example degree of elbow: 60=.577
45=.414
30=2.00
example in your situation
45 degree elbow 48x20=72, 48 + 24 half your check is 24=72 thats your centre line radius...
(1.414x36 offset)-2(.414x72)
=50.904-2(29.808)
=50.904-29.616
=21.288 thats the length of the duct in between your on your two 45 degree elbow...

i hope this help you...
What about the total height of the fittings? Is there a formula for that?
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  #22  
Old 12-18-2016, 11:51 PM
tinstructor tinstructor is offline
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Default finished total length of offset

Yes there is! The good news is, most of the work is already done once you've calculated the rise to the center of the elbows and the duct or pipe between them.

>Total length=sqr(hypotenuse^2-offset^2)+ 2x (elbow 1/2 rise)

>the hypot. is slant side of the triangle all the way to the center of the angle,without subtracting 2x the rise. You will already have calculated this. sqr is square root


>the rise to the center of the elbows also will already have been calculated and,of course,the offset is known.

I hope this is clear and helps you.
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  #23  
Old 12-19-2016, 12:40 AM
Bradleyc1982 Bradleyc1982 is offline
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Thanks very much, could you put this in a sum for me to help m understand the calculations you would have to do?
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  #24  
Old 12-20-2016, 02:56 PM
Bradleyc1982 Bradleyc1982 is offline
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Quote:
Originally Posted by tinstructor View Post
Yes there is! The good news is, most of the work is already done once you've calculated the rise to the center of the elbows and the duct or pipe between them.

>Total length=sqr(hypotenuse^2-offset^2)+ 2x (elbow 1/2 rise)

>the hypot. is slant side of the triangle all the way to the center of the angle,without subtracting 2x the rise. You will already have calculated this. sqr is square root


>the rise to the center of the elbows also will already have been calculated and,of course,the offset is known.

I hope this is clear and helps you.
I think I understand now, does it work for all different angles e.g. 30 and 60 degrees??
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  #25  
Old 12-21-2016, 09:27 AM
tinstructor tinstructor is offline
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Default ..does this work for ALL degrees of elbow offsets ?

Yes,it does, and since its not possible to memorize all of the different trigonometry numbers, you should let your math calculator do the work.

> if you like I'll give you a mini tutorial on the trig keys on your calculator.

> sine,cosine,tangent,(sin, cos,tan)& their inverse functions are your friends.
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  #26  
Old 12-21-2016, 10:59 AM
Bradleyc1982 Bradleyc1982 is offline
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Quote:
Originally Posted by tinstructor View Post
Yes,it does, and since its not possible to memorize all of the different trigonometry numbers, you should let your math calculator do the work.

> if you like I'll give you a mini tutorial on the trig keys on your calculator.

> sine,cosine,tangent,(sin, cos,tan)& their inverse functions are your friends.
That sounds great thanks for all the help
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  #27  
Old 12-23-2016, 11:18 PM
sanjayrana56@yahoo.com sanjayrana56@yahoo.com is offline
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Default GI Ducting

Hello everyone,

I am new in Hvac field.my boss said to me making BOQ for ducting. i already make but confuse in TDC & TDF & profile for duct. will you please explain me how can choose TDF,TDC & profile for ducting?
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  #28  
Old 01-05-2017, 09:34 AM
Bradleyc1982 Bradleyc1982 is offline
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Quote:
Originally Posted by tinstructor View Post
Yes,it does, and since its not possible to memorize all of the different trigonometry numbers, you should let your math calculator do the work.

> if you like I'll give you a mini tutorial on the trig keys on your calculator.

> sine,cosine,tangent,(sin, cos,tan)& their inverse functions are your friends.
I'd like to take you up on your offer if that's ok when you get a chance mate. Thank you very much
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  #29  
Old 01-12-2017, 07:55 PM
tinkev tinkev is offline
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Default 30 or 60 degree elbow

for 30 or 60 degree elbows do you still use ".414 x CLR" or is there a different number other than .414 ?
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  #30  
Old 01-12-2017, 08:55 PM
tinstructor tinstructor is offline
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Default .414 multiplier for all angles of offsets ????

No. Each angle has its own unique rise.

> Do this; On your calculator,enter the degree of elbow that you are using. Divide it in half.Leave this answer on the screen and press the tangent(tan)key. This is your multiplier. Use just the first 3 digits to the right of the decimal.
>I hope this is clear and helps you.
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