. . . & lots more than just a conventional ductulator  

• Duct converter module:

Sometimes, you need to convert duct sizes between round, rectangular and oval duct.

• Irregular shaped duct sizing module:

Whether you like it or not, you're forced to design an irregular shape duct that fits into the available space. See example here.

• rhoAIR module:

More often, you need to find the dewpoint, air density and other psychrometric properties of a given air temperature condition. See  aRhoAIR page for an explanation.

• Louvre sizer module:

In planning or design stage, you need to give structural opening sizes or louvre sizes to architects or structural engineers. This tool will help you to save time.

• Fan Motor kW module:

To calculate electrical power requirement for electrical engineers.

• Convert KW-Amp module:

Very often, given a fan motor KW, you want to find Amp.

• Duct gauge/weight module:

This tool helps you to calculate duct weight, perimeter and surface area for rectangular, round and oval duct. Built-in duct gauge selections are Galvanized steel, Stainless steel and Aluminium duct. 

• Threaded rod sizer module:

Need to size and select hanger rod size, this tool is specially built for that purposes. It also calculates tensile stress and maximum load. See tRod Sizer page for explanation.

• Hello! Condensation module:

This app helps you to predict surface condensation occurrence, calculate U-value and heat gain. See Details and Examples page.

Note: aDuctulator does not calculate fitting / dynamic loss. 

Built-in Features:

Unlike the conventional hand-held ductulator which is built for round duct sizing with equivalent rectangular duct sizes, velocity  & friction loss rate for round duct, pre-calculated for the duct roughness of 0.09mm and limited duct sizes, aDuctulator offers you the flexibility in duct sizing for various duct shapes and different materials such as concrete duct, flexible duct, etc.

aDuctulator is designed to offer you the greatest flexibility in duct sizing: 

• options for Equal Friction method or Velocity method or by Duct Dimensions or find Airflow.

• options for round or rectangular or oval duct shape.

• use Colebrook equation in solving friction factor. 

• use hydraulic diameter (not equivalent diameter of round duct) for rectangular and oval duct sizing.

• duct converter for round, rectangular & oval duct.

aDuctulator gives you detailed results like Flow area, Hydraulic diameter, Reynolds number, Friction factor and Velocity pressure, if you need it and save the results.

Duct Sizing Methods

aDuctulator offers 4 commonly used methods of duct sizing:

1) The traditional Equal Friction Method of duct sizing is often preferred as it is easy to use and less time-consuming. This method uses a constant pressure loss per unit of duct length. Generally, 0.8 Pa/m (0.1 in.wc/100 ft) of constant pressure loss per meter run has been widely practised in duct sizing.

Because there are practically unlimited number of duct sizes for a given design air flow, the duct sizing problem is solved by iteration technique.

2) Velocity method is often used when acoustic requirements or minimum air transport/duct velocity is given. 

3) Find friction loss rate by Duct Dimensions method. This comes handy when you need to determine the friction loss of an existing or a given duct size.

4) Find airflow method. This is useful especially for an existing duct: how much airflow can a given duct size handle?

Units in aDuctulator

Both SI & IP units are available in aDuctulator. 

Did you know? . . . (1) Equivalent cross-sectional Area! 

If you want the same duct friction loss rate, it is inappropriate to convert duct size based on equal cross-sectional area, be it from round to rectangular or square to rectangular. This is because rectangular duct is less efficient than round duct; rectangular duct is less efficient than square duct. See example below, the flow areas (ie, cross-sectional areas) are different for the same duct frictional loss rate. 

Did you know? . . . (2) Hydraulic diameter vs Equivalent diameter!  

For ducts with shapes that are not round, hydraulic diameter is not equal to equivalent diameter. For circular duct, hydraulic diameter is the same as the diameter of the round duct.

For any duct shapes, hydraulic diameter = 4 x cross-sectional area / perimeter. aDuctulator uses this approach to find duct sizes.

For rectangular duct, equivalent diameter = 1.30 x {(Width x Height)0.625 / (Width + Height)0.25}. 

For oval duct, equivalent diameter = 1.55 x (cross-sectional area)0.625 / (perimeter)0.25.

Example 1: Duct Sizing at job site (in SI units)

An existing duct 600mm (W) x 500mm (H) carrying airflow of 8000 CMH needs to be flattened to 300mm (H) to achieve the desired ceiling height.

Find the new duct size.

Solutions:

Step 1: Find duct friction loss rate for the existing duct.

Step 2: Calculate new duct size with the given height constraint.

The following results are computed by the aDuctulator:

Example 2: Determine Fan Motor kW rating . . .  

Fan Total Pressure = Fan Static Pressure + Velocity Pressure

A tunnel ventilation fan of 43 m3/s (154800 CMH) requires a total pressure of 1800 Pa. Determine the fan absorbed power.