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ePF Loop Pdrop
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...Pumping Mainline
a push for mobility and productivity - the ultimate multiple pipes friction loss calculator on Windows 
 Loop pipe pressure drop (head loss) calculation (Windows)

multi-purpose solutions for total pump head, pipe network pressure drop calculation in series (branch) pipes + loop ring main pipe network



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


ePF Loop:  a multi-purpose Pressure Drop (Head Loss) calculation 

Managing pipe pressure drop (total pump head) design calculations every other day...... there is no magic to the solutions. But, we  (designers and solution providers) are always looking for a better way to do things and deliver the solutions in a quicker and easier way .... easy.Pipe.Friction (ePF)



Goal: A practical yet simple, efficient way of pressure drop (head loss) calculations for different field services.


Target: Provide solutions to meet your deliverables at anytime, anywhere.


Applications: Pipe distribution network in series (single or multiple) and/or pipe in single loop ring main; General water piping, Sewerage and drainage pumping system, Chilled water and Condenser water piping, Irrigation piping, Fire hydrant, Fire hose reel, Wet rising main, Standpipe, etc.

Note: This program is not designed for fire sprinkler 'Tree or Grid' system and the like. Also, it is not designed for pipe network with two loops conjoined by a common link pipe.

Results: Just-in-time results to meet your deliverables. Results are saved in text file. You can reformat, cut and paste, edit, and so on to suit your desired format.


 Loop  Pressure Drop (Head Loss) Analysis: Hardy Cross Method. . .  

Hardy Cross method and Hazen-Williams equation or Darcy-Weisbach equation are used in solving loop ring main pipe network. The flow (Q) and Pressure drop (Pdrop) in each pipe segment are iteratively solved by relationship equations between head loss and flow.




Any series (branch) pipe that joins the loop (upstream and/or downstream) is calculated separately using series pipe calculation.




The total pressure drop (head loss) in the system is the summation of all components causing resistance to flow.




 Built-in tools: making calculation experience more simulating . . .  

Important to note: This program is designed with one set of units system for all calculations. For input simplicity, built-in units conversion tools are available. see pictures explanation

Flow, Q Diameter, D Length, L Pressure Velocity 
 l/m mH2O m/s
 Pressure Drop (Pdrop) is displayed with the following units
 mH2O, bar, kPa, ftH2O, psi


Various selection and calculation tools are provided. They are:

- Flow unit converter, Length unit converter, Pressure unit converter.

- Pipe diameter sizer, Pipe material & ID selection.

- Valve & Fitting selection (Equivalent length Le method, or Resistance coeff K method).

- Orifice plate pressure drop calculator.


Flow, Q input selection 


Pipe Diameter, D input selection

Pipe Length, L input selection 


Valve & Fitting input selection (Le or K method)

Pipe material selection (Hazen C, or Darcy e) 



Static pressure input selection


Operating pressure input selection


User-defined input selection





 Loop Model: Classic illustration with the simplest loop pipe network  



Important to note:

The Loop Model adopted in ePF Loop program is a single-input source, a single loop with one or more discharge outlets. Each pipe segment can have an outflow discharge. There is no limitation to the number of pipes that can be created in the system. Options available for major and minor losses calculations are Hazen-Williams equation (with equivalent length Le method), or Darcy-Weisbach equation (with resistance coefficient K method).





The simplest loop pipe network is formed by 3 pipes as shown in the diagram below. The loop has a single-input source. For a given looped pipe network, the outflow discharges (Qout) are known. However, the flow (Q) in each pipe of the looped pipe network and its head loss (Pdrop) are unknown. This involves solving non-linear equations iteratively by the Hardy Cross Method, i.e.,


Q = 0 at a junction (known as Kirchhoff's law)

Pdrop = 0 around a loop (known as Kirchhoff's law)


Pdrop = K * Qn  where

n=1.85 for Hazen-Williams formula

n= 2 for Darcy-Weisbach formula

K= factor dependant of pipe length, diameter & roughness




Notice that the calculated flow and pressure drop in pipes 102 & 103 are negative (-ve). The -ve flow (Q) means the flow in that pipe segment is in an anti-clockwise direction. Likewise, the -ve pressure drop (Pdrop) in that pipe segment simply indicates that the flow is in the anti-clockwise direction.



The results obtained using Hazen-Williams equation is shown below:





The results obtained using Darcy-Weisbach equation is shown below:




 Series Model: Single pipe or Multiple pipes pressure drop 


In series model, ePF Loop program is capable of computing pressure drop in single pipe or multiple pipes without limitation to the number of pipes that can be created in the system. The methods employed in the calculations are: 



(1) Hazen-Williams equation and equivalent length (Le) method for valves and fittings.


(2)  Darcy-Weisbach equation and resistance coefficient (K) method for valves and fittings.


The total friction loss is the sum of all the friction losses in each section of the pipe plus local losses.



Note: for series pipe pressure drop calculation on Android, see mPPD - multiple Pipe Pressure Drop (Android).







 Series + Loop Pipe Network: Loop ring main network  




For a pipe network that contains series pipes and a single loop ring main, the pressure drop in the series pipes and looped pipe are calculated separately. The total pressure drop (head loss) in the system is the summation of series + loop components.

See below Hydrant ring main system example. 




If you need to plot 2 pumps in parallel curves and system curve, see CurveFit Tracer.




>> worked example (Series + Loop): Hydrant ring main system



>> see results comparison example (ePF Loop vs a 3rd party program)



>> worked example (Series): Pumping main system



>> Analysis example: Loop pipe ring main, see at  







ePF Loop

Price: US $12.90



OS requirements: Windows 7, 8, 10, . .

(Note: this software does not work on Windows XP).                              



see pictures explanation


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For product enquiry, email me.




in SI Units


 For input simplicity, units conversion

tools are



see pictures explanation