What equation is used for duct weight?

Find the area of duct first.
for example duct size is2' X3' and length =10'.
find area ((2 +3)X2)X10' =100 sq.ft.
=100/(3.28X3.28) = sq.meter =9.3 sq.meter if the duct is24 gauge then kg/m2 =4.5 approximately multiply area(m2) by kg/m2 we will get weight in kg.
for above case it will be9.3 X4.5 =41.8 Kg.
Note: You should know the duct gauge and its dimension and some standards like what is kg/m2 of each gauges

- WIEGHT(KG) FOR THIKNESS1 MM DUCT =8KG PER1M SEQUER (8KG/M2) . 

-  YOU CAN CALCULATE WIEGHT FOR DIFFIRENT THIKNESS ( EXAMPLE FOR0.8MM=6.4 KG/M2.

- THEN YOU CAN CALCULATE  THE ARIA OF DUCT = [2(WIDTH+DEPTH)*LENGHT].

- FINAL DUCT WIEGHT( KG)=  ARIA * WIEGHT FOR1M SEQUER AS PER THIKNESS .

 * ( duct cross section area A=2*(L+W 

DUCT material volume V = A*lenght of duct

 

M= D * V

M :duct weight  kg

 kg/m3     D:galvanaized steel densty       

you get D from smacna  tables by knolege of gauge or thikness 

 

WIEGHT( KG)= DUCT AREA(M2) * DUCT GAUGE WIEGHT/ M2

                         = [2(WIDTH+DEPTH)*LENGHT] * DUCT GAUGE WIEGHT/M2

first find the area of duct then duct size is2' X3' and length =10'. find area ((2 +3)X2)X10' =100 sq.ft. =100/(3.28X3.28) = sq.meter =9.3 sq.meter if the duct is24 gauge then kg/m2 =4.5 approximately multiply area(m2) by kg/m2 we will get weight in kg. for above case it will be9.3 X4.5 =41.8 Kg. 

WHEN WIDTH AND HEIGHT OF DUCT ARE GIVEN IN METRIC UNITS ALONG WITH L/S WHAT WOUL BE THE AREA OF THE DUCT IN MM

 

AND CONVERSION PLEASE

 

 

The formula for calculating the Theoretical Weight of galvanized sheet in lb/ft2 is:

TW = t x40.833 – CF (1)

Where: TW = Theoretical Weight in lb/ft2

t = actual sheet thickness in inches

40.833 = weight in lbs of1 ft2 of1” thick steel

CF = Coating Factor in lb/ft2

For example; galvanized sheet0.020 inches thick with a G90 coating has a coating factor of0.006 lb/ft2,

based on the relationship in (1) and a typical actual G90 coating weight of0.96 oz/ft2. Therefore:

 

TW =0.020 x40.833 –0.006 =0.8107 lb/ft2