Free Software for Sprinkler Hydraulic Calculations by Alan Ashfield

Free Program AACALC12 for NFPA 13 Pipe Schedule Sprinkler Systems - 21st July 2015

I present a completely free, unique and innovative program for the Pipe Schedule sizing method within the NFPA 13 "Installation of Sprinkler Systems" Rules. You simply have to prepare your CAD layout drawing following a few guidelines as described below (as I am sure you already do) and AACALC12 will read this in, join all the pipes and heads together, size them to the appropriate table, provide a full quantities list that can be quickly priced up and to create another DXF file of the pipe sizes so determined for merging with the original drawing.

In my recent Email discussions with various Fire and Fire Protection authorities / associations around the world about my offer to produce specific software for their use / sale for the full hydraulic calculation of sprinkler protection systems in their own languages (just click here for more details), it soon became clear that a vast majority of systems installed in most countries were, in fact, end- and centre-fed pipe arrangements of light and ordinary hazard sized to the NFPA pipe schedule method. Unfortunately, there were then no programs to assist with such calculations, mainly because they are very easy to do and just not worth the extra time in preparing the information needed.

However, most sprinkler designers, contractors and installers now use CAD programs, either the free LibreCAD or paid-for, commercially available ones, to prepare their layout drawings (invariably a 2D plan) and this contains nearly all the information needed to determine the pipe sizes based on the number of heads it supplies. The only item missing is any change of elevation (rises and drops) needed to turn it into a 3D view so one can see elevations and isometric views. Therefore if you draw out all the rises / drops as a smaller diameter circle than is used for the upright / pendent heads, and optionally give the positive (= up) or negative (= down) change as text (eg. +678 or -3000), then AACALC12 can incorporate them, size all the pipes and work out the elbows / tees etc. for the fitting and pipework quantities list.

This page therefore describes all the options and features of my new ENGLISH only program if this matter is of interest and you seldom get involved in the full hydraulic calculation of looped, gridded, ESFR, roof/rack, special risk etc. systems that all my other programs listed on this website can help with.

AACALC12 plan

Click here to download AACALC12.EXE [21.07.15 550 kB] now. When run it should look like the above screen after clicking on "Example". It is suitable for all versions of Windows from 2000 right up to 10 (except RT) with a minimum screen size of 1366 x 768 pixels. [29.07.15] All these screen-shots have been taken from my WINDOWS 10 computer, newly updated today.

Information needed on your CAD drawing

When creating your 2D sprinkler layout drawing for a specific project, you need to follow the guidelines listed below so that AACALC12 can understand what this is meant to represent :-

  1. UNITS of measurement to be millimetres (mm) not imperial - everything has to be TO SCALE, you cannot draw a line of say, 3000 mm and then dimension it as 3456 mm!
  2. HORIZONTAL PIPES (and nearly flat pipes, say under 45 degrees slope) - to be drawn as a LINE entities (not 'polyline', '3dline' or 'xref') on a set layer (eg. 'spipes', see later but any line thickness, style or colour) representing the feed mains, cross mains and branch lines between heads. Each section of pipe between changes of direction, cross mains or branch lines between sprinkler heads must be drawn as a separate line from a START X and Y co-ordinate nearest the source out to the END X and Y co-ordinates. So if there are 6 heads along a branch line then there has to be 6 LINES joining them together in the direction away from the cross-main - even if 'pendent' type (where the convention is that the pipe 'line' passes through the head 'circle' or 'upright' type (where the pipe 'lines' stop at the 'circle' representing the head). You cannot just draw one 'line' connecting all the branch lines together or all the heads across a range - they have to be separate as they could be of a different size of course. My example job makes this clear.
  3. VERTICAL PIPES (and almost vertical ones, say over 45 degrees slope) - each to be drawn as a CIRCLE entity (not 'arc' or other constructs) on a the same layer as the horizontal pipes at the same X and Y co-ordinates as the PIPES that join to it (eg. 'spipes' but with any line thickness, style or colour) of a set RADIUS (eg. '50' but see [3] later)
  4. UP or DOWN dimensions - to be drawn as a TEXT entity on the same layer as the two previous items (eg. 'spipes' but any height, font, orientation, thickness or colour) representing the change of elevation / height in mm (eg. '+456' if rising 456mm or '-567' if dropping 567mm) at an INSERTION POINT within 100mm of the centre of the matching vertical rise/drop circles (ie. o +455 not -3000 o) - you do not have to do this for all such circles as AACALC12 has an option to preset these to a 'default' value if extreme accuracy is not required (see [4] later)
  5. SPRINKLER HEADS to be drawn as a CIRCLE entity on the same layer as the previous 3 items but a different set RADIUS (eg. '100' as given in [2] later) from the correct X and Y INSERTION POINT. They will be 'pendent' type if the pipe lines join together at or near the centre (or have a vertical pipe circle at the same X and Y co-ordinates with a minus dimension given) or an 'upright' type if the pipe lines stop at the circumference of the circle (or have a have a vertical pipe circle at the same X and Y co-ordinates with a positive dimension given)
  6. ALL other items about the building (the walls, partitions, columns, windows, doors, notes etc), any other services (the electrical lighting, heating and ventilation ductwork and equipment / notes etc) and other notes, pipe sizes, title block etc pertaining to your sprinkler design are to be drawn on additional layers (not 'spipes') and will therefore be completely ignored by AACALC12.
  7. In other words, AACALC12 only looks for the 'spipes' (or other set) LAYER for LINES (pipes), CIRCLES (rise/drop or heads) and TEXT (+ rise or - drop in mm) entities and skips everything else in your DXF file. These are automatically produced by the free LibreCAD program but if you have bought another CAD package (which saves to a proprietary format such as DWG, then you will need to 'Save As' a text-based DXF format as used by AutoCAD 11 or 12, which gives you a useful backup as well). These DXF files are a simple text format (item-value on separate lines) and can be viewed or amended with NOTEPAD or similar (but not WORDPAD or other word-processing software).
  8. I have provided an example DXF file that you can study or, perhaps a better idea would be for you to create a very small layout drawing (eg. just 2 branch lines of 3 heads) based on these notes and see what AACALC12 makes of it rather than spending hours (or days!) preparing or modifying an existing large CAD layout drawing and possibly getting nowhere fast because of layer or circle size differences.
  9. Please note that my program assumes you have followed the NFPA 13 Rules as regards the layout, spacings, arrangement, options etc. (which I just cannot repeat here) and you have used the layers and entities described above otherwise AACALC12 will not give the correct results. Note also that you do NOT mark on the pipe sizes on the 2D layout DXF drawing as my program will do this but if you do, such text items will be ignored.

Operation of free program AACALC12

When first run, the main screen will be blank and there will be just two 'PAGES' visible across the top of the screen as shown below :-

AACALC12 start page

I suggest you begin by clicking on "Example" (to see a simple end-fed system as shown next) but you can choose "Exit", "Open" (or "Last" if there) for those specific options if required :-

AACALC12 Example

Here all the lines, circles and text in the DXF file are on the correct layers of the correct circle sizes, so all the pipes, rise/drops and heads are shown in blue as given on the status line at the top. If the information is not right, then the items will be shown in grey (see below). Note I have specifically made the 4 heads on the second range of pendent type (compare with previous screen-shot) just to show how these are handled. There is also a new 'PAGE' shown called "Convert to 3D and Size Pipes" so click on this for now to see :-

AACALC12 3D view

Here we have produced an isometric view (from SW corner as leftmost option) with the pipe sizes in mm (as the middle option text). Try clicking on these two options to see the different views (plan, elevations and isometrics) and green text (lengths, heights, number of heads and size or no text at all). Note there is another new 'PAGE' called "Quantities List / Estimate" that shows :-

AACALC12 Quants list

You may need to click on the bottom half of the screen or press the [PgDn] key to see the rest of the data but you will note the confirmation of the size and arrangement of the system and the list of quantities and sizes of the pipework, head elbows/reducers, head tees and other elbows and tees. See "Pricing rates for the pipework and fitting quantities" below for more information. You can click on "Print" to get a printout on your inkjet or laser printer or produce a PDF file if you have a suitable printer driver from or similar or can select "File Options and 2D plan" to choose "Exit" to finish now from the first page if required. The program has automatically created another DXF file by appending SIZES to the file name (so if your job is called FRED.DXF then the pipe sizes are in FREDSIZES.DXF) - simply go back to your CAD program, read in FRED.DXF (you may need to select 'Zoom All', 'Zoom Extents', 'Auto Zoom' or other option to view it full screen) and then DXFIN or similar to read in FREDSIZES.DXF to combine the layout with the sizes in mm at the centre of all the pipes. Yes I have deliberately missed out one 'PAGE' called "Drawing Options" so please select this now to see :-

AACALC12 drawing options

Along the top are 6 options / questions - press the [TAB] key to move between them or just click your mouse when over that item :-

  1. Sprinkler pipes / head layer name - this is where you enter / change the layer used to store the LINE, CIRCLE and TEXT entities representing your sprinkler layout drawing - I suggest 'spipes' but you can use any valid name or number as used in your CAD program. If you have the wrong title here then the pipes, rise/drops, sprinkler heads and up/down dimensions will be shown in grey rather than blue.
  2. Head radius in mm - this is where you enter / change the size of the CIRCLE entities representing the pendent / upright sprinkler heads. If you hold your mouse over the yellow box, then a short hint will pop-up explaining that there is a 10% tolerance on the entered value (I suggest 100 mm as a suitable number but you may disagree) to accept the entity as a sprinkler head rather than a rise/drop circle - see [3])
  3. Rise circles radius mm - enter or change the size of the CIRCLE entities representing the rise/drop vertical pipes. Again there is a hint explaining the 10% tolerance in the value - I suggest 50 mm but you can put in any number from 10 to 100 but be careful to make it more than 30% difference in the [2] and [3] values lest they get mixed up!
  4. Average vertical rise in mm - enter or change this value to represent the nominal change of elevation (height in mm) from the cross-main at the rise circles for end- or centre-fed branch lines. Yes, I know, they will not be all the same in different parts of the drawing even though one normally does not run the mains to fall to drain back to the source. However, the pipe size does not change with length, just the number of heads it supplies, so an average figure here is surely accurate enough for the fitting quantities and estimate. If you want to spend time entering the actual rises in mm, then just add the +mm text markers adjacent to the smaller radius circles and those dimensions will be used instead.
  5. Branch lines slope in degrees - normally 0 for horizontal pipes between heads on all the branch lines but you can put a slope here (say 6 degrees) if that is the case. Again, I am well aware this one value may not be applicable throughout the entire drawing but it just did not seem worthwhile to mark on the rare slopes if applicable. It will only change the total pipe lengths by 1.0 divided by the cosine of the angle.
  6. NFPA 13 Pipe Schedule sizing table - just select the appropriate item based on the hazard, pipe type and maximum spacing of branch lines along the cross mains or spacing of heads along the branch lines. Only pipe sizes 25 to 150mm are stored as 200mm steel or copper pipe would be far too expensive to use and you would be far better off redesigning the system for full hydraulic calculation using my FREESHP program or similar.

If any of these items are wrong, then the 2D drawing will be shown like that below where I have changed the 'spipes' layer to 'xxx' :-

AACALC12 incorrect drawing options

Zooming in and out of drawing

All drawings are full size on the screen but for larger sprinkler systems you may want to zoom in to show a specific part at a bigger scale. This is done in a similar way for both the 2D and 3D views as follows :-

  1. From the full size plan view, click on "Zoom in" (there is a prompt hint) and that button will disappear
  2. Position your mouse over the bottom left hand corner of the part of the drawing that you wish to investigate
  3. Hold down the left hand button (not click) and then slide your mouse up and to the right, drawing out a purple rectangle on the screen as you do so
  4. Release the left hand mouse button when at the top and right of the area of interest
  5. That part enclosed by the purple rectangle will be immediately redrawn (although the pipes / heads may be slightly different based on the aspect ratio of the rectangle to the screen dimension)
  6. Click on the "Zoom out" button now at the top of the screen to go back to the full size view
  7. For the 3D view on the "Convert to 3D and Size Pipes" page, you can choose to select another view from the leftmost option such as plan, elevations or isometrics and the green text for that option to show the lengths, heights, number of heads and size or no text at all.
AACALC12 zoomed in plan AACALC12 zoomed in isometric

Pricing rates for the pipework and fitting quantities

AACALC12 will give you a list of the quantities for each pipework size used and all the elbows / tees on your drawing but will NOT price them up. From my repeated Email discussions with estimators in lots of sprinkler companies over the last few years, they are extremely reluctant to divulge their rates to anybody, not even with other members of the same company let alone software developers like me!

They jealously guard their figures and never reveal the factors to apply for the location / type of project, height of working, if new or retrofit and other essential items that govern the total estimate / price for installing the sprinkler system for a given project. I have therefore just sidestepped this option so you can just copy the numbers down from the screen into the secret spreadsheet or print out my worksheet for manual calculation.

Obviously, if somebody wants to store the prices for all the combinations of size, pipe type and fitting arrangement within AACALC12 and can give me all the details / factors involved, then I will amend the program accordingly.


The free AACALC12 program can cope with much larger drawings than I have shown above, so here are some more screen-shots as an example. Remember, all you had to do was to produce the 2D plan using the guidelines specified and my software will do the rest :-

AACALC12 2D plan AACALC12 isometric AACALC12 quants list

This gives a complete description of all the options and features of AACALC12. My Email address is at the top of this page for any comments or queries - just have AACALC12 as the 'Subject' and they will be promptly answered by the same person who wrote the program. All software packages described on this encrypted website are completely free and can be downloaded anonymously :-

Click here to download AACALC12 [21.07.15 550 kB] now - no Email address or registration is needed.

You should create a new folder on your computer, say, C:\aa3progs or C:\aacalc12 and copy the downloaded file to that and can then right-click on it to copy a shortcut to your desktop or "pin to taskbar" as required. Thank you for downloading my program - I hope you find it useful and there are many other free programs that may be of interest on this website.

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