The Air Duct Calculator is a PERL/CGI script which allows users to size
ductwork and calculate duct pressure losses. The program is written in the PERL
programming language and is intended for use on the World Wide Web via the
Common Gateway Interface. The program is designed for use by Mechanical
Engineers who design air distribution or exhaust systems for Heating Ventilating
and Air Conditioning systems.
The program allows users to input a desired flow rate, a limiting velocity,
air pressure, air temperature, the length of the duct, and the duct material.
The program then calculates the duct cross sectional area, the circular duct
diameter, rectangular duct equivalents (with aspect ratios of 1.0 through 4.0),
air density, fluid viscosity, Reynold's number, relative roughness, the Moody
friction factor, the Colebrook friction factor, the pressure loss, and the duct
friction loss per unit of duct length.
The program uses the Moody equation, the Colebrook equation, the Darcy-Weisbach
equation, the perfect gas laws, and the Huebscher equation.
Slide-rule type duct calculators designed for standard air and galvanized
steel ductwork do not allow users to correct for non-standard air conditions, or
for other types of duct material. The Air Duct Calculator allows users to input
any type of duct material, and can input any air temperature and pressure. The
program will then calculate air density and air viscosity for precise pressure
- Fluid Mechanics and its applications by James W Murdock, PE
Houghton Mifflin Co.
- Heating Ventilating and Air Conditioning Analysis and Design
by Faye C. McQuiston and Jerald D. Parker
John Wiley & Sons.
- Flow of Fluids Through Valves, Fittings, and Pipe
Technical Paper No. 410
The Crane Company
- ASHRAE Fundamentals 1993
The American Society of Heating Refrigerating and Air Conditioning Engineers
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This program was developed by: Michael
J. Rocchetti PE