ACADS-BSG has released a new computer program for calculating the pressure loss of a series of airconditioning ducts and fittings to enable the fan pressure for a building ductwork system to be determined.

Called Dlphin, its key benefits are the increased accuracy of airconditioning ductwork design and much quicker calculations compared with current manual calculations.

The user enters the ducts, starting from the fan, and working down towards a selected terminal. For each duct entered, the fittings are selected and the program then calculates the pressure loss in each length of duct and with each fitting. Supply ducts and fittings are entered on one screen and return ducts are entered on a second screen.

The program can also size individual ducts basedon an entered pressure drop/meter, maximum duct velocity and a size increment. The Colbrook-White formula is used to size the duct. The program, however, also displays a range of equivalent sizes either side of the “design size” based on a nominated fixed height, fixed width or fixed aspect ratio.

The program is said to have many features that make data input easy, including a convenient selection for for fittings. Ducts can be circular, rectangular or oval and a range of duct materials can be selected for setting the duct surface roughness. Duct sizes can be entered as clear internal dimensions or as sheet metal sizes in which case the program deducts the insulation thickness from the entered duct height and width or diameter.

A comprehensive range of fittings and their associated loss coefficients as a function of air flow and shape are stored in the program. The data for these duct fittings have been extracted from the AIRAH Duct Design Application Manual DA2 on which the program is based.

Source: Building Products News.