- 9 -
1
1
12
7
14
8
33
2
4
24
24
33
CAUSING AIR TO CHANGE DIRECTION CAUSES TURBULENCE AND RESTRICTS FLOW IN
A SYSTEM.
IF USING FLEXIBLE METAL DUCT - INCREASE ALL MULTIPLIERS BY 50% (12 BECOMES
18 - ETC.)
THIS EASY TO USE WORKSHEET IS FOR 600 CFM OR LESS.
UNDER “QTY USED” ENTER HOW OF EACH SECTION YOU WILL BE USING.
IN THE FIRST TWO ROWS - ENTER HOW MANY FEET OF EACH TYPE OF STRAIGHT DUCT
YOU WILL BE USING (I.E. FOR 20 FT ENTER 20, FOR 30FT ENTER 30).
ENTER THE NUMBER OF EACH TYPE OF TURN YOU ARE USING AND THE TYPE OF END CAP.
MULTIPLY ACROSS EACH ROW THE “MULTIPLIER” x “QTY USED” TO GET THE EQUIVALENT
FEET FOR THOSE COMPONENTS.
ADD UP ALL THE VALUES IN THE “EQUIVALENT FEET” COLUMN.
DUCT PIECE
DESCRIPTION
MULTIPLIER
QTY USED
EQUIVALENT
FEET
1’ of 6” Round Duct
1’ of 3 1/4“ x 10” Rect. Duct
6” 90 Degree Elbow
6” 45 Degree Elbow
3 1/4” x 10” 90 Degree
3 1/4” x 10” 45 Degree
3 1/4” x 10” Side 90 Degree
3 1/4” x 10” x 6” Round
3 1/4” x 10” x 6” 90 Degree
6” Round Wall Cap w Damper
3 1/4” x 10” Wall Cap w Damper
6” Round Roof Cap
TOTAL EQUIVALENT FEET SHOULD BE LESS THAN 100
estimating total equivalent feet in
a duct
