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Dear customers & visitors, as Microsoft is closing down its SharePoint soon, .TT pocketEngineer softDesign is relocating its home to Google site at
 a Ductulator (Android) - HVAC duct sizing

more than just a Ductulator . . . the ultimate duct sizer for Android OS platform



To take a glance at all pocketEngineer software and OS requirements, click Overview.

For Windows OS, see Ductulator Plus.


Note: aDuctulator (Android) and Ductulator Plus (Windows) are not the same.


 aDuctulator:  Duct Sizing on Andorid OS 

aDuctulator, a duct sizing calculations program for Android OS platform,  is specially designed by a professional engineer to replace the conventional hand-held ductulator. It is more than just a Ductulator.

Aim: creating a mobile design environment
for the practising engineers & designers in today's mobile world.

Results: Instant solutions at your fingertips.



 Duct sizing for Rectangular, Round or Oval shape with 3+1 common sizing methods (i.e., equal friction, velocity, by duct dimensions + find airflow). Detail results such as velocity pressure, hydraulic diameter, reynolds number, friction factor, relative roughness and flow area are included.
 Rectangular and Oval duct sizes are obtained by direct iteration algorithm method, i.e., not converted from round duct size.
 you're in control; full control and exact on input parameters, i.e., no sliding bar type of input method which can be difficult to control to exact numbers. Distinct input (white) and output (yellow) fields.

 different duct materials selection (Galv. steel, Spiral, Aluminium, Carbon steel, PVC, Duct board, Duct liner, Flexible duct and Concrete).

 find duct fictional loss rate by Duct Dimension method (useful design tool for existing duct).

 find airflow for a given duct sizes (useful design tool for existing duct).
 built-in Duct Converter, rhoAIR, Louvre Sizer, Fan Motor kW, Convert KW-Amp, Duct gauge/weight, Threaded rod hanger sizing, txt file Viewer.
 Duct converter module to convert duct sizes between round, rectangular and oval duct.

 Irregular shaped duct sizing module to size polygon shape duct with built-in polygon shape builder. See example here.
 rhoAIR module to find air density and other pyschrometric air properties at state point.
 Louvre sizer module to size louvre opening required for structural opening.
 Fan Motor kW module to calculate electrical power consumption.
 Convert KW-Amp module to convert electrical KW - Amp, and calculate KVA.
 Duct gauge/weight module to find duct weight, perimeter and surface area for rectangular, round and oval duct with built-in duct gauge selections (Galvanized steel, Stainless steel and Aluminium duct).
 Threaded rod sizer module to size and select threaded hanger rod with built-in metric-english series of rod sizes, tensile stress calculator and maximum load calculator.

 Hello! Condensation module .... to calculate surface condensation, U-value and heat gain. See examples on this page
 txt file Viewer module to view and edit saved results.
 SI & IP units setting.
 Save results function.





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


Note: modules contained in aDuctulator is not the same as Ductulator Plus. 



. . . & lots more than just a conventional ductulator  


It has built-in modules like


 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 conditions. See  aRhoAIR page for 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 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.


Pictures explain everything - . view aDuctulator explained 



 Duct Sizing Methods  


aDuctulator offers 3 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. Click "calculation explained" for detail.

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.


Parameter SI Units  IP Units
 Friction loss ratePa/m in.wc/100 ft 
 Duct roughness mmft 
 Air Volume





 Duct dimension mm in.
 Duct velocity m/s FPM
 Flow areamft
 Velocity pressure Pa in.wg
 Hydraulic diameter mm in.


 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 diffierent for the same duct frictional loss rate.


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


For duct with shapes that are not round, hydraulic diameter does not equal to equivalent diameter. For circular duct, hydraulic diameter is the same as the diameter of a 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 an airflow of 8000 CMH needs to be flattened to 300mm (H) to achieve the desired ceiling height.
Find the new duct size.



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:


 Step 1 results

 Step 2 results

Duct Friction Loss Rate calculations

(by Duct Dimensions method)


Retangular Duct sizing......
Duct height (mm) =500
Duct width (mm) =600
Air volume (CMH) =8000
Duct roughness (mm) =0.09
Duct velocity (m/s) =7.4
Friction loss rate (Pa/m)=0.9781

detail results...........
Area, A (sq.m) = 0.30

Relative roughness, e/Dh = 0.000165
Hydraulic dia, Dh (mm)= 545.5

Reynolds nos, Re = 268,283
Friction factor, f = 0.016205

Velocity pressure, Pv (Pa)= 33.03

Equal Friction Method calculations


Retangular Duct sizing......
Friction loss rate (Pa/m) =0.9781
Duct roughness, e (mm) =0.09
Air volume (CMH) =8000
Duct height (mm) =300
Duct width (mm) =1100

Duct velocity (m/s) =6.7


detail results...........
Area, A (sq.m) = 0.33

Relative roughness, e/Dh = 0.000191
Hydraulic dia, Dh (mm) = 471.2
Reynolds nos, Re = 210,908
Friction factor, f = 0.016916

Velocity pressure (Pa) = 27.34


  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. 





safety factor 


safety factor

 Air flowrate (CMH)154800154800 
 Total pressure (Pa)18001800 
 Fan efficiency (%) 73 73
 Shaft Power (KW) 106.07 106.07
  Safety factor (%) 010 
 Motor (KW) 106.07116.68 
Motor Efficiency (%) 9292

Absorbed Power (kW)


 Example 3:  Stress calculation for fire-rated ductwork hanger rod (in SI units) . . .  


see tRod page.



Now on Android OS,



at Android Market 


Download now:

product detail       



OS requirements: Android.         


For Windows, see    

Ductulator Plus

To Purchase & Download to your Android device:


at Android Market



For product enquiry, email me.



 in SI & IP units



 view aDuctulator explained 



 Sizing Method selection



Duct Converter module 


rhoAir module 


 Louvre Sizer module



txtRW module for result viewer



Fan Motor kW module




 Convert KW-Amp




 Duct Gauge/Weight module




Threaded Rod Sizer module