Free Software for Sprinkler Hydraulic Calculations by Alan Ashfield

Free Hydraulic Calculations on the Internet

Manual calculation example (16.02.17) ...

I am sometimes asked by Email to show how my programs will get the
same answers as a manual calculation done with a pocket calculator,
so here is an example to explain the various formulas and equations
used for just 3 heads being supplied by 25, 32 and 40 mm pipes
along a branch line / range.
1) Assume a sprinkler head "K" factor of 80 on an Ordinary Hazard
scheme where the density is 5 mm/min and the area covered per head
is 12 sq.m, so we just have a minimum flow rate Q of 5 x 12 which
is 60 L/min, but what is the pressure?
2) Using the formula Q = K x square root of P (the pressure in
bars), we need to transpose this to give P in terms of the known
K and Q so is Q / K all squared which comes to 0.5625 bars.
3) If we assume a nominal 25 mm diameter pipe of type M to BS10255,
the actual internal bore is 27.35 mm and the Hazen-Williams "C"
factor is 120, so what would be the pressure drop of a 4 m length
(the reducing elbow at the head is included in the "K" factor) run
flat with no change in elevation?
4) Using the Hazen-Williams pressure drop formula :-
                605000.0 x L x Q
Pressure drop = ----------------
                 1.85       4.87
                C        x D
5) We have L = 4.0 m, Q = 60.0 L/min, C = 120 and D = 27.35 mm so
this works out to be
605000 x 4 x 1947.959007 / 7022.395823 / 9953646.213
which equals 0.06744157 bars.
6) The pressure at the second head is therefore this value plus
0.5625 bars which is 0.62994157 so giving a flow Q of 80 x square
root 0.62994157 ie. 63.49508682 L/min (about 3.5 more than the end
head because it is nearer to the source).
7) So the flow Q in the second 32 mm pipe is now 60 + 63.4950862 =
123.4950868 L/min along with L = 4.0 m, C = 120 but D is now 36.05
mm bore. The new pressure drop is
605000 x 4 x 7405.457734 / 7022.395823 / 38205743.91
which equals 0.066796438 bars.
8) The pressure at the third head is therefore this value plus
0.62994157 bars which is 0.696738008 so giving a flow Q of 80 x
square root 0.696738008 ie. 66.776667 L/min (again about 3.5 more
than the previous head).
9) So the flow Q in the third 40 mm pipe is now 123.4950868 +
66.776667 = 190.2717538 L/min along with L = 4.0, C = 120 and
D = 41.95 mm. The new pressure drop is
605000 x 4 x 16475.6476 / 7022.395823 / 79929053.53
which equals 0.071034263 bars.
10) The pressure at the start of this pipe is this value plus
0.696738008 which comes to 0.767772271 bars at a flow rate of
190.2717538 L/min.
11) So although we have 3 heads of nominal flow of 60 L/min, the
actual flow rate is just over 190 L/min (not 180) and the
pressure needed is 0.768 bars (not 0.56).
12) Perhaps this will demonstrate why nobody but nobody would ever
produce such hydraulic calculations manually - you are just bound
to make an error somewhere so getting the WRONG answer!
13) May I suggest you now download and run my very simple AACALC10
program and check the above calculation is the same.
You need to select "New" and type in 3 pipes as follows, pressing
{TAB} to replace the spaces below :-
100 110 41.95 120 4.0 0.0 0.0 80.0 60.0
110 120 36.05 120 4.0 0.0 0.0 80.0 60.0
120 130 27.35 120 4.0 0.0 0.0 80.0 60.0
14) It will only take a minute or two to type these values in,
noting each time that the hydraulic calculations are repeated
so that you see, on the top line :- 
Source duty = 190.3 L/min at 0.768 bars (ie. the same as above).
15) If you think that the 36.05 and 41.95 mm pipe sizes are too
big [as they are], then you simply redo the manual calculation
steps (7) to (10) and see how long it takes you.
16) So for 27.35, 27.35 and 36.05, the source is 198.8 L/min at
1.048 bars and for 27.35, 27.35 and 27.35, the source is 198.8 L/min
at 1.505 bars - is this what you calculated?
17) If you still have AACALC10 open, then you only need change
the pipe sizes and the calculations are done instantly.
AACALC10 - introduction
18) If AACALC10 is too complicated for you, then my AACALC8 will
repeat the same sums for a complete range from "page 2" simply
by setting K = 80, density = 5 and area to 12 - thats all. You
can even do 2 pipe friction loss calculations at the same time ...
AACALC8 - page 3 of 5
19) I have also provided FIRSTHCP where DEMO 3 is
this exact example to help you learn hydraulic calculations.
FIRSTHCP - View calculations
20) I can also suggest that you download the complete source
code of FREESPRAY for a real example of how such
calculations are carried out for complete sprinkler systems,
not just for 3 heads along a single branch line / range!

Alternatively, just CLICK HERE to download my suggested hydcalc.ods file of the above arrangement.

[27.07.17] If you want your own, free, personalised hydraulics calculator and/or have not used a "spreadsheet" type program before, then just download LIBREOFFICE onto your computer. I suggest you do this via (it is on the far right hand side and you may want some of the other items listed). It only takes a few minutes so then run the LIBREOFFICE program, select LIBRECALC and type the first 5 numbers and [Enter] in the cells A1 to A5.

In A6, type
= 60500*SQRT(A4*A4+A5*A5)*A1^1.85/A3^1.85/A2^4.87 [Enter]
If you don't want the sloping length to be used, then just type
A4 instead of the SQRT( .. ) part.
In A7, type
=A5*0.098 [Enter]
In A8, type
=A6+A7 [Enter]
In A9, type
=A1/(0.04712*A2*A2) [Enter]
and as you do so, those values will be calculated and shown. You
can then enter the text items in B1 to B9 as needed and can format
the rows / columns with the required font, size, number of decimal
places as desired and SAVE it. That's all.
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These are the hydraulics programs you have been looking for ...

For the EN12845 RULES used throughout Europe, there are the AACALC7, CAD2ENRULES, EASYSHP, VSHP, HYD, IPDS43 and AAVIEW7 programs.

For the NFPA 13/15 + FM GLOBAL RULES used worldwide, you can choose FREESHP, CAD2HCP, FIRSTHCP, ISO2HCP and AACALC9 with a CAD program for Pipe Schedule systems called AACALC12 plus FREEWATERMIST for NFPA 750 water mist systems.

For BOTH the above sprinkler rules, I offer AACALC8, AACALC10, AACALC11 and my latest FREEHC software packages.

For the BS9251:2014 systems, you can use NEW3RD.

All these are in METRIC units only, except FREEHCP which is in the AMERICAN units of feet, inches, gpm and psi.

The 5 programs I added in 2017 were FIRSTHCP, CAD2HCP, CAD2ENRULES, ISO2HCP and FREEHCP so perhaps you should try those first. If you want me to review your very first job done with any of my programs, then you can Email the corresponding data file.

Just click on the underlined links above to read more about them and to download the single EXE files and please remember they are all FREE! If you have NEVER done any fire sprinkler hydraulic calculations before then you should NOT PURCHASE AN EXPENSIVE PROGRAM OFF THE INTERNET. You will never be able to use it as it will have unfamiliar questions and really critical design parameters - one mistake here and you will just generate a page of random numbers not the correct flows, pressures, velocities etc. Much better to try one or more of my free ones on your early projects.
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