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easy multiple Pipes Pressure Drop (mPPD) calculation using Darcy-Weisbach or Hazen-Williams equations; a "flavour" in quick estimating pressure drop |
Specially engineered to be easy, practical and flexible, this multiple Pipes Pressure Drop (mPPD) app provides quick engineering design solutions for single or multiple pipes friction losses based on:
(1) Hazen-Williams equation and equivalent length (Le) method for valves and fittings.
(2) Darcy-Weisbach equation and equivalent length (Le) method for valves and fitings.
(3) Darcy-Weisbach equation and resistance coefficient (K) method for valves and fittings.
The program is capable of computing major and minor friction losses with various built-in valves and fittings selections. Note that mPPD calculates the total pipe pressure drop in the pipe network, not the total system (pump) head. If you need to calculate total dynamic head (i.e., pump head), see Easy Pipe Friction (ePF) Loop program for Windows.
Highlights:
- Add [+] row after the specified row number.
- Delete [-] row at the specified row number.
- No limitation for the number of rows that can be created.
- LongClick feature on the input textboxes (Q, D, L, Le/D or K, C or e) for selections.
- Valves and fittings can be put on a separate row by itself, if you prefer to see the friction loss contribution separately.
- Each row (pipe) is calculated and presented separately for velocity, Reynolds number, friction factor, friction loss and summation of pressure drop.
- Built-in comprehensive lists of valves and fittings Le (equivalent length) or K (resistance coefficient) selections.
- Built-in various pipes DN or ID selection.
- Built-in Hazen-Williams C coefficient or pipe roughness e selections.
- Set preferences for flow unit, maximum velocity limit and Hazen-Williams C coefficient or pipe roughness e.
- SI or IP units setting.
- Save input data.
- Open input data.
- Save results.
- Built-in text file viewer for result file.
The first of its kind in a familiar spreadsheet table style on Android, this multiple Pipes Pressure Drop (mPPD) calculator is intended to lessen your routine and tedious engineering work.Tremendous engineering effort and time has been spent to develop this comprehensive application for all engineers and designers.
the Legacy of Hazen-Williams equation |
A "flavour" in pipe frictional loss calculation, Hazen-Williams' empirical equation is the most commonly adopted method since its pipe friction coefficient, C, is not a function of velocity or pipe diameter or Reynolds Number. It is to note that Hazen-Williams equation is only valid for water (preferably 4 - 25 ^{o}C or 40 - 75 ^{o}F).
Engineering calculations are estimates, to the best of his/her knowledge. Work smart! We don't need complex equations or complicated iterative methods to solve simple engineering applications, and the result remains as an approximation of reality. Knowing its limitations is more important than anything else. Hazen-Williams equation does not account for temperature and viscosity of the water. It is used for turbulent pressurised pipe flow.
In SI units, the Hazen-Williams equation is as follows:
where
P = frictional loss of pressure (bar per m of pipe)
Q = flow (lpm)
D = pipe internal diameter (mm)
C = Hazen-Williams coefficient for the type of pipe
What are Minor Losses in pipes . . . |
These are local head (energy) losses caused by valves, elbows, bends, tees, reducers, etc.
In mPPD, two methods are used to compute the minor losses caused by valves and fittings as follows:
(1) Equivalent Length (Le) method for Hazen-Williams and Darcy-Weisbach equations.
(2) Resistance coefficient ('classic' K) method for Darcy-Weisbach equation.
Again a "flavour" in accounting for minor losses, Le is the equivalent length of pipe with same resistance as the fitting/valve. The published Le/D data in Crane TP 401 and others is for C = 120 (steel pipe). The Le can be converted as necessary for pipes of other C values by multiplying a factor as stated in NFPA and others:
C | 100 | 110 | 120 | 130 | 140 | 150 |
---|
Factor | 0.714 | 0.850 | 1 | 1.160 | 1.330 | 1.510 |
---|
There is no Le/D data available for reducer, expander, entrance, exit, orifice, nozzle, etc. In this case, Le/D can be determined using the following formula:
Le/D = K/f
where
K is the 'classic' resistance coefficient, as in | |
f is the Darcy friction factor, as in | |
For example, if we know K for sudden Exit into a tank is 1 and f is 0.012192 ( solved by colebrook equation ), then Le/D = 1/0.012192 = 82.
Did you know ? . . . pressure drop vs head loss |
Don't confuse yourself with pressure drop and head loss.
Pressure drop = | |
Head loss = | |
Pipes of different diameters connected end to end to form a pipe line is said to be in series. The total friction loss is the sum of all the friction losses in each section of the pipe plus local losses.
In mPPD, each row (pipe) is calculated and presented separately for velocity, Reynolds number, friction factor, friction loss and summation of pressure drop. Different pipe material can be specified for each row (pipe).
Note: For multiple Series pipe with a loop ring main on Windows, see easy Pipe Friction (ePF) Loop (Windows).
Let's get stuff done . . . Easy Pipe Friction way |
The following illustrates easy pipe friction with mPPD and its capability. Determine the pipe friction loss with water mass flow of 15 kg/s from Tank A to B as illustrated in the schematic below.
(1) Sharp entrance.
(2) 100mm dia Ductile iron pipe, 5m length.
(3) 1 Strainer.
(4) 1 Gate valve.
(5) 1 Check valve.
(6) 100mm dia Ductile iron pipe, 10m length.
(7) 1 Standard elbow.
(8) 1 Reducer.
(9) 50mm dia Copper pipe, 100m length.
(10) 1 Standard elbow.
(11) 50mm dia Copper pipe, 10m length.
(12) 1 Butterfly valve.
(13) Sharp exit into tank.
Step 1: convert mass flow to volumetric flow
(using the built-in flow converter)
Step 2: input data | Step 3: results |
| |
Remarks: The above example illustration (using Hazen-Williams equation and Le method) shows that the pipe size is undersized from row 9 to 13.
Worked Example 1 . . . Quickly Estimating Pressure Drop in Pipe (English Units) |
Consider a 16-in (ID = 15.624-in) Sch 40S stainless steel system. The piping system contains 100 ft of pipe, 6 long-radius (R/D=1.5) 90^{o} elbows, 2 side-outlet tees, 2 gate valves (fully open) and an exit into a tank. The water flow rate is 13.314 ft³/s. What is the pressure drop through this system?
Compare the results computed by:
(1) Darcy-Weisbach equation with K method.
(2) Darcy-Weisbach equation with Le method.
(3) Hazen-Williams equation with Le method.
(d) Hooper's 2-K method (refer to Windows program: Pipe_f.Loss)
The table below shows the results computed by the different methods in mPPD program.
| Darcy + K (mPPD) | Darcy + Le (mPPD) | Hazen + Le (mPPD) | Hooper's 2-K method (Windows Program: Pipe_f.Loss) |
Total pressure drop | 3.41 psi 7.87 ft 0.24 bar | 3.60 psi 8.31 ft 0.25 bar | 3.51 psi 8.09 ft 0.24 bar | 3.53 psi 8.14 ft 0.24 bar |
Result Printouts: |
(1) Darcy-Weisbach equation with K method
(2) Darcy-Weisbach equation with Le method
(3) Hazen-Williams equation with Le method
(4) Hooper's 2-K method (see Windows program: Pipe_f.Loss) |
Worked Example 2 . . . fire hydrant system (SI units) |
Determine the total pressure drop in pipes, valves and fittings for the fire hydrant piping system as shown in the schematic below.
Compare the pressure drop computed using:
(a) Darcy equation with Le method.
(b) Hazen equation with Le method.
Design data:
Q (flow rate) = 38 l/s.
Pipe material = Ductile iron pipe.
Pipes, valves and fittings data:
(1) Pipe total run = 100m, 150mm diameter
(2) Isolation gate valve = 1 no.
(3) Standard 90^{o} elbow = 4 nos.
(4) Meter = 1 no.
(5) Gate valve = 1 no.
(6) Check valve = 1 no.
(7) Check valve = 1 no.
(8) Tee = 1 no.
(9) Reducer = 1 no.
(10) Pipe total run = 3m, 100mm diameter
(11) Gate valve = 1 no.
(12) Standard 90^{o} elbow = 1 no.
The following are the results computed by mPPD program:
Result Printouts: |
(a) Darcy equation with Le method
(b) Hazen method with Le method |
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For multiple Series pipes + Loop ring main network pressure drop, see ePF Loop (easy Pipe Friction) on Windows.
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