Answer / kaleeswaran

Duct Area = (Width + Height)*2*Length

Answer / prakash suhane

Size of Duct depends on various factors like :

1) Cfm of duct
2) Required static pressure in duct
3) Shape of duct piece like bent, offcet, length, round etc
4) If any heating or cooling element to be install in duct.

A smart HVAC engineer takes various onsite decisions to
avoid unneccessary pressure drop.

Answer / srikanth

In measurement wise we measure in square meters and in flow
wise we measure in cfm(Cubic feet per Minute)

Answer / choudhry m m

actually for designing the ducts we have to refer the table
like ASTM, ASHRAY etc in which we have to chec the flow
accordingly we have to check the size

Answer / sathya

To measure the ducting, need to know the depth, width and
length of the duct... says w=2500,d=500,l=500 (w*d)*2*l

so (2.5*.5)*2*.5=1.25sqmtr

the gauge of the duct varies as per the size of the duct
upto 750 - 24g, 750-1500-22g, 1500-2250-20, above 2250-18g
GSS sheet

regards

sathya

Answer / ram pratap yadav

To measure the ducting, need to know the depth, width and
length of the duct... says w=1400,h=600,l=9925
,a=(w+h)*2*l/1000000

so (1400+600)*2*9925=39.7sqmtr

the gauge of the duct varies as per the size of the duct
upto 750 - 24g, 750-1500-22g, 1500-2250-20, above 2250-18g
GSS sheet

regards

ram pratap yadav

Answer / mithun

To measure ducting

1. the amount of cfm flowing though the duct

2. by keeping the velocity constant or by friction constant
we can decided the duct

Answer / mohammed fayaz

q=av
q= quantity of air (cfm)
V= velocity of air (fpm)
a= area of the room

velocity is =900 from ashrae notes
Ex;

4 tr

1tr = 400 cfm
4tr = 4*400= 1600 cfm

Q = 1600 CFM
V = 900 CFM

Q = AV
A = Q/V
A = 1600/900
1.77 Ft sq
TO convert in mt sq multiple with 0.093
1.77*0.093
= 0.165 mt sq

assume that the duct ht is 0.3
u ll get 55 X 30 cm duct size.
thats it

Answer / md ashwaq

To measure ducting
1) If u do not have width and height of a duct
Use duct manualator or duct sizer software,from which u
will be knowing the width and height by inputting airflow
(CFM) data and headloss.
2) By using the formula...2(width"+height")*length"/144
You will be getting the total duct estimation in square
feet..
3) If the height of the duct exceeds 30 inches ..26 guage
sheets should be used..

Answer / sd.muthahar basha

Is the question asked for measuring a duct or designing a
duct...
(a) to measure a duct a scale or tape is sufficient
and
(b)to design a duct Mc Quay`s duct sizer software is more
than sufficient...
there are three methods for designing a duct
1.Equal fiction method
2.static regain method
3.velocity reduction method

1TR IS = ? CFM

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