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the home of .TT pocketEngineer softDesign - where pocketEngineer software lives...
 a Pipe Sizer (Android) -  pipe sizing

quick design solutions for pipe sizing + friction losses, chilled-water flowrate, drainage gravity flow...




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

For Windows OS, see pocketPipe.


Note: aPipeSizer (Android) and pocketPipe Sizer (Windows) are not the same.


 a Pipe Sizer with Android

a quick design solution for your pipe design 

A quick design solution for pipe sizing + pipe friction losses (with valve and fittings losses), chilled-water flowrate, condenser water flowrate, hot water flowrate, drainage gravity flow, drainage pipe gradient, pump motor KW, Pump NPSHa and NPSHr, Water density and viscosity, etc.


Pipe sizing & pipe friction loss calculations have never been easy. Not anymore! With aPipeSizer, you can do your pipe design and sizing at anytime, anywhere...

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

Results: Instant solutions at your fingertips.




 Pipe Sizer:- pipe sizing for general water applications; extendable to pipe frictional loss calculation with Hazen-Williams equation and Le method for valve and fittings, or Darcy-Weisbach equation and K method for valve and fittings. Select pipe DN/ID sizes from a list of pipe material table.

 Pipe ID + Volume:- Select pipe diameter (DN or ID) from the pipe material table and calculate pipe fill volume.

 Water density and viscosity:- calculate water properties for density, dynamic viscosity and kinematic viscosity at given temperature.

 HVAC Water:- find capacity or flowrate or delta Temperature for chilled-water, condenser water & hot water.

 Drainage Gravity Flow:- calculate flow capacity or pipe diameter for gravity flow pipe using most popular Manning equation.

 Drainage Pipe Gradient:- find pipe gradient, pipe invert levels, pipe run, pipe drop for sewer/sanitary drainage system.

 Pump NPSH:- calculate NPSHa (available) and NPSHr (required) with various built-in selections including liquid vapour pressure and pipe friction losses. See calculation example on this page.

 Pump motor kW:- calculate absorbed power for pump. See calculation example on this page.

 Convert KW-Amp:- convert KW-Amp calculation for 1 or 3 phases AC supply.

 "save-to-file" function with built-in text file viewer.

 in individually selectable SI-IP Units.


 Pipe Sizerdesign explained. . .  
Pipe Sizer employs 2 options for pipe friction loss calculations, i.e., Hazen-Williams equation with valve & fittings Le method, or  Darcy-Weisbach equation with valve & fittings K method. Darcy-Weisbach method is generally considered more accurate than Hazen-Williams method. However, Hazen-Williams method is very popular since its friction coefficient, C, is not a function of velocity or pipe diameter. It is to note that Hazen-Williams equation is only valid for water at temperature 4 - 25 oC (40 -75 oF).


You can choose water density and pipe materials with built-in database. 





Darcy friction factor, f, is solved by  Serghide's explicit equation - an approximation of the implicit Colebrook-White equation. Serghide's solution closely mirrors Colebrook's implicit solution within 0.0031%. 


Note: now, aPipeSizer can calculate minor (valve and fittings) loss using Le method or K method.



For 2K method valve & fittings pressure drop calculations, see   Pipe_f.Loss program (Windows) using Darcy equation and Hooper 2K method for a single pipe calculation.


For multiple pipes friction losses, see   multiple Pipes Pressure Drop (mPPD) using Hazen-Willaims and Darcy-Weisbach equations with Equivalent Length (Le) and Resistance Coefficient (K) methods.




Worked Example (in IP units)

A 16-in diameter ductile iron cement-lined pipe carries city water at a flow rate of 8 ft3/s. What is the pipe friction loss through a pipe length of 100 ft? Assume the city water at 50 oF for density and dynamic viscosity.


Printouts Result:

Flowrate = 8 ft3/s
Diameter = 16 in
Velocity = 5.7 ft/s


Friction loss by Darcy equation....
Pipe length = 100 ft
Water Density = 62.428 lb/ft3
Dynamic viscosity = 1.306 cP
Pipe roughness = 0.0001 ft
Reynolds Number = 543456
Friction Factor = 0.013993
Friction loss = 0.5356 ft H2O




 HVAC Water formula:

Cooling or Heating Water. . .  

The cooling or heating water flowrate-capacity-dT calculation is based on the following formula:


              q = Q x rho x Cp x dT


  where  q = heat rejection rate or heat load, kW

               Q = water flowrate, m3/s

               rho = density of water, kg/m3

               Cp = specific heat, kJ/kg.K

               dT = temperature difference, oC


 Did you know. . .

Heat Rejection Factor (HRF) 

Conventionally, condenser water flowrate for water-cooled chiller is calculated as 3 USgpm/ton. This is equivalent to Heat Rejection Factor (HRF) of 1.25. With more efficient chillers being produced, the Heat Rejection Factor is lower than convention. In the absence of actual heat of compression of compressor, the following approximations may be used for design purpose:


0.8 kW/ton chiller: HRF = 1.25

0.7 kW/ton chiller: HRF = 1.22

0.6 kW/ton chiller: HRF = 1.19

0.5 kW/ton chiller: HRF = 1.16

0.4 kW/ton chiller: HRF = 1.14


Note: the above approximations are only applicable for vapor compression chiller. Absorption chiller has much higher HRF.


Simply put, if you know the compressor kW from chiller selection data, the Total Heat Rejection (THR) is


THR (kW) = chiller cooling capacity (kW) + compressor kW power


HRF = THR / chiller cooling capacity


Note: 1 kW power is the equivalent of 1 kW refrigerant cooling load.



Worked Example (in IP units)
Design/size the chilled-water and condenser water flowrate for a water-cooled chiller of capacity 340 tons.

Step 1: Calculate chilled-water flow rate
Water temperature @ 50 oF

Density = 62.428 lb/ft3

Specific heat = 1.002 btu/ibm.F


Chiller Capacity = 340 Ton
dT = 10 oF
Flowrate = 813.58 USgpm


Step 2: Chilled-Water Pipe Sizing Calculation
Flow rate = 813.58 USgpm

Pipe diameter = 6 in.

Pipe velocity = 9.2 ft/s (velocity too high!!!)


Frictional loss by Darcy equation....

Pipe length = 100 ft.

Water Density = 62.428 ib/ft3 (Water @ 50 oF)
Dynamic viscosity = 1.306 cP
Reynolds number = 328356
friction factor = 0.016832
Friction loss = 4.4600 ft H2O (friction loss rate per 100ft is too high?? Expected as the pipe velocity is beyond the norm. Calculate again..... as easy as 1,2,3 with aPipeSizer.)

Step 3: Calculate Condenser water flowrate

Water temperature @ 86 oF

Density = 62.178 lb/ft3

Specific heat = 0.998 btu/ibm.F


Chiller Capacity = 340 Ton

Heat rejection factor = 1.25 (in the absence of known heat of compression of compressor)

Total heat rejection = 425.00 Ton
dT = 10 oF
Flowrate = 1024.48 USgpm




 Drainage Gravity Flow

Manning equation. . .  



Manning equation is the most widely used formula for gravity flow calculation in a pipe. In English units, the Manning equation is stated as follows:




Q = flowrate (ft3/s)

n = manning roughness coefficient

A = flow area (ft2)

R = hydraulic radius (ft) = flow area/wetted perimeter

S = slope (gradient) of pipe (ft/ft) = drop/distance


Full bore, 3/4 bore, 1/2 bore and 1/4 bore flow conditions are calculated.




Worked Example - Pipe carrying capacity (in IP units)
Calculate the flow rate and its velocity for full and partial flow conditions in a 6-in diameter ductile iron cement-lined pipe, if the gradient of the sanitary drainage pipe is 1 in 100.



Find Flow....
Pipe diameter (in) = 6
Manning Coeff. = 0.013
Slope gradient = 1: 100



Flow Capacity of Pipe (by Manning Equation)....

 Bore Q (ft3/s) V (ft/s) A (ft2)
 Full 0.56 2.86 0.196
 3/4 0.51 3.24 0.158
 1/2 0.28 2.86 0.098
 1/4 0.08 2.00 0.038

[Q=Flowrate; V=Flow velocity; A=Flow area]




Worked Example - Required sewer pipe size (in IP units)
A concrete pipe sanitary sewer with "n" = 0.013, slope of 0.6 percent and required full flow capacity of 110 cubic feet per second.

Determine the pipe size.



Find Diameter....

Flowrate, Q (ft3/s) = 110
Pipe diameter, D (in) = 48
Manning Coeff. = 0.013
Slope gradient = 1: 166.7 (Note: 0.6% = 1 in 166.7)



Flow Capacity of Pipe (by Manning Equation)....

 Bore Q (ft3/s) V (ft/s) A (ft2)
 Full 111.25 8.85 12.566
 3/4 101.45 10.04 10.110
 1/2 55.63 8.85 6.283
 1/4 15.24 6.20 2.457

[Q=Flowrate; V=Flow velocity; A=Flow area]



 Drainage Pipe Gradient

sewer/sanitary drainage system . . .  


Expressed as percent, gradient = (fall/run) x 100% 

Expressed as 1 in xx, gradient = 1: (run/fall)


 Invert level is the "floor" level of a pipe.


 Worked Example (in SI units)
Case (a): 200mm diameter pipe at gradient 1: 120 (0.83%)

Case (b): 150mm diameter pipe at gradient 1: 90 (1.11%)

Find the Invert Level at Inspection/Access Chamber No. 2


  Case (a) Case (b)
 Invert Level (I.L.) at Chamber No. 299.583 m 99.444 m
 fall (drop) 0.417 m 0.556 m




experience yourself on the Android: aPipeSizer

at Android Market 


Download now:

product detail   


OS requirements: Android        


for Windows OS, see pocketPipe


To Purchase & Download to your Android device:





@ Android Market


For product enquiry, email me.




in SI and IP Units 

 aPipeSizer - main selection page 


 view aPipeSizer explained 



Pipe Sizing for general water service applications



  Pipe Sizing extendable to Pipe Friction Loss calculation


Valve & Fittings (K method) selection




Pipe ID + Vol module 



HVAC Water module



Pump Motor kW calculation



Convert KW-Amp module




Drainage Gravity Flow module



 Drainage Gravity Flow module 



Drainage Pipe Gradient calculation