Square Duct To Round Duct Formula

The table below can be used to compare equivalent diameters for rectangular and round circular ducts.

Square duct to round duct formula.

Measured in inches of water column in wc it acts equally in all directions and is independent of velocity. To then convert that to volume you multiply the resulting area by the length. D diameter of duct in inches. The table is based on the ducts friction loss formula.

2001 ashrae fundamentals p. Static pressure is the pressure that causes air in the duct to. 12 inches per foot. This is the number of square inches in the duct area.

This online air duct calculator is used to calculate the velocity of air flow feet per minute fpm and feet per second fps through any shaped circle square or rectangle ductulator with either diameter sides or area. Static pressure is the outward push of air against duct surfaces and is a measure of resistance when air moves through an object like duct work. Divide by 144 to determine how many square feet are in the duct area. Gustafson g 0 single wall round rectangular to round conversion de 1 30 ab 0 625 a b 0 250 a length of one side of rectangular duct inch b length of adjacent side of rectangular duct inch de circular equivalent of rectangular duct for equal friction and capacity inch source.

Area surface area of duct in square feet. Multiply this number by 3 14 pi to get the area of the round duct in square inches for example 16 x 3 14 50 24 square inches. Equivalent round duct size for a rectangular duct equivalent round duct size for a rectangular duct can be expressed as deq 1 3 x a x b 0 625 a b 0 25 where deq equivalent diameter a one dimension of rectangular duct inches b adjacent side of rectangular duct inches equations for flat oval ductwork. The rectangular dimensions and the air flow volume are adapted to the equal friction loss.

Then measure the length of the duct in inches and multiply by the circumference. Duct areas in square feet can be calculated by using geometry rules for round areas. Measure the distance across the duct in inches then multiply by 3 14159 if the duct is circular to find its circumference in inches. Air duct also termed as ductulator is a passage that is used to provide fresh air into rooms buildings etc air ducts may be in circular square and in rectangular shapes.

The equivalent diameter is the diameter of a circular duct or pipe that gives the same pressure loss as an equivalent rectangular duct or pipe.