Engineering-xls: Linx Duct Friction Calculator Excel Sheet

Monday, January 28, 2019

Linx Duct Friction Calculator Excel Sheet

File Size: 552 Kb

In fluid flow, friction loss (or skin friction) is the loss of pressure or “head” that occurs in pipe or duct flow due to the effect of the fluid's viscosity near the surface of the pipe or duct. In mechanical systems such as internal combustion engines, the term refers to the power lost in overcoming the friction between two moving surfaces, a different phenomenon.

The major loss, or friction loss, in a circular duct in galvanized steel with turbulent flow can for imperial units be expressed

Δh= 0.109136 q^1.9 / d_e^5.02 (1)

where

Δh = friction or head loss (inches water gauge/100 ft of duct)

d_e = equivalent duct diameter (inches)

q = air volume flow - (cfm - cubic feet per minute)

For rectangular ducts the equivalent diameter must be calculated.

Pressure vs. head

Content :- 1. Instruction
2. Linx Duct Size Calculator
3. Duct Calculator
4. Flat Oval to Round

5. Number of Conduits @ equal velocity

6. Duct Diameter

7. SMACNA 2005 standards for +10 iwg and nominal weight lb/sf

How to use this Excel Sheet :-

None of the cells are locked or protected. Keep a backup copy.
YELLOW boxes indicate where you can input numerical values as deemed necessary
All pressure drops are expressed in inches water gauge per 100 linear feet unless user redefines "Length"
Calculations are based upon ASHRAE 1993 Fundamentals, Chapter 32, Duct Design
Temperature, barometric pressure, elevation, air density, and conduit roughness coefficients are all user definable .

TAB "Rect to FO & Round" calculates equivalent flat oval and round for a given rectangular duct cross section
TAB "Rect to FO & Round" calculates multiple round conduits based upon "equal friction" and "equal velocity"
TAB "Flat Oval Tables" tabulate Lindab's published standards
TAB "Calculator" is a stand alone calculator for rectangular, flat oval, and round
TAB "Flat Oval to Round" is a stand alone calculator to convert flat oval to equivalent round
TABS "Equal Velocity" and "Equal deltaP" is used to make calculations for "Rectangular to FO & Round"
TAB "Weights" is used to make calculations for "Rectangular to FO & Round"