Hydraulic Calculation Examples
FHC hydraulic calculation software can calculate almost any type of water-based fire protection system, from the conventional tree-pipe configuration to the more complex roof-and-rack gridded systems. FHC is not limited to sprinkler systems; many users worldwide use our software to aid in the design of high- and low-pressure water mist systems using conventional pump sets, pressurised cylinders and constant-pressure pumps.
Below are several fire sprinkler hydraulic calculation examples that demonstrate the versatility of our software and its ability to calculate any type of water-based fire protection system. If you do not see the type of project you are working on, we have probably seen it before. If you require further information, please don't hesitate to contact us.
ESFR fire sprinkler system with addition rack protection
ESFR fire sprinkler installation installed into major car manufacturer’s parts facilities and is somewhat bespoke in its design. The roof level sprinklers are ESFR 25mm with a K-factor of 360 and a minimum head pressure of 3.5 bars. In addition, the rack storage below is protected with a 20mm sprinkler with a K-factor of 115 and a minimum head pressure of 1.0 bar. The final water demand requirements for the system were 9849 L/min @ 9.0 bar, and the design, aided by FHC, achieved 98% design efficiency.
This FHC hydraulic model consisted of 810 pipes, 154 loops and 26 heads. It was calculated on a Pentium VI computer in under 0.1 seconds.
Example of a multiple loop hydraulic calculation in FHC
An FHC hydraulic calculation that demonstrates its capabilities and shows a perfect balance of flows through the pipe network consisting of 106 pipes and 15 loops in its calculation. The system has loops within the loop, four in all. The FHC software easily produced the hydraulic calculations for this system, showing its versatility.
Fire sprinkler system in a tree pipe work configuration
Fire sprinkler systems often use tree pipe work configuration in the system design, and although this configuration is not as hydraulically efficient as a loop or grid system, it still has its uses.
For complex buildings such as schools, residential care homes and systems that require a dry fire sprinkler installation, a tree system can be the way to go. The pipe work in tree work configurations can be sized in a conventional way by using pre-sized pipe tables for the number of sprinkler heads or by fully calculating the hydraulics by hand without much difficulty, but even for small systems, they are still very time-consuming and prone to human error.
By using FHC you have all the advantages of full hydraulic calculations in helping you reduce your pipe sizes and/or the water demand. Furthermore, the calculations will not have the human error factor and will only take a fraction of a second to calculate, allowing you, the designer, more time to optimise the system and reduce costs.
Deluge fire protection system
Deluge installation of any type can be modelled with the FHC program. In this example, medium-velocity sprayers protect a vertical cylinder. Within the FHC hydraulic model, we specified an area for each nozzle and a minimum design density of 10 mm/min.
NFPA 750 hydraulic calculation for a water mist system
A calculation for a high-pressure water mist fire protection system designed to NFPA 750. For high-pressure systems, you should use the Darcy-Weisbach pressure loss equation, which accounts for both the fluid's absolute viscosity (centipoises) and its density.
The water supply can be from a pressurised cylinder, a constant pressure pump, or any other type of water supply. Custom nozzle and pipe data files can be used for the hydraulic modelling of water mist systems. Canute can provide customised pipe data files and nozzle data files based on any water mist manufacturer's data.
Hydraulic calculation for EN 12854 High Hazard roof system
FHC is being used to hydraulically module an EN 12845 high hazard fire sprinkler system. The system is for roof protection only and is designed to provide a density of 10mm/min over 260 m2.
The model has 412 pipes, 30 loops and 31 operation heads (K80 min pressure of 0.5 Bar), FHC calculated this system in 0.06 seconds.
Storage tank protected with a foam pourer system designed to NFAP 11
This hydraulic model represents a large storage tank with a fixed cone roof and is protected by three foam chambers. The foam chambers are located above the tank's liquid level, and the deflector is inside the tank to distribute the foam solution across the surface.
The number of foam chambers is determined by the tank diameter for a fixed cone or open top tank, and the flow rate can be calculated by multiplying the area by the required density.
The tank in this example has a diameter of 30m and therefore a surface area of 707m2. If we base the design density on 4.1 mm/min, this will give us a minimum flow rate of 2899 L/min and will require a minimum of two foam chambers, but to give a faster foam distribution, we have used three. Also, the volume of foam from each pourer is reduced, which will allow for a smaller riser pipe to each of the foam chambers. For this design, we have used 80mm Viking Model FC foam chambers and each chamber will protect the 236m2 area and require a minimum of 699 L/min discharge. By using the manufacturer's design table, we can determine that we will require a minimum pressure of 4.14 Bar at the foam chamber inlet.
With the above information, we can now proceed to start the hydraulic calculation for the systems, but instead of using a sprinkler or head as the output devices, we can specify in FHC the required flow rate and pressure which is required for each foam chamber on our system in the optional items section in the Project Data. When we calculate the hydraulic model in FHC, we find that we will require a source duty of 2122 L/min @ 5.525 Bar.
You can find out more information about protection of storage tanks in NFPA 11: Standard for low, medium, and high-expansion foam
Hydraulic calculation for a fire hydrant system
FHC can hydraulically model fire hydrant systems, configured as simple layouts or loop systems. Any number of hydrants can be flowing, and you can specify different flow rates and pressures for each hydrant if required.
If the hydrant system is to be fed from a pump supply, you can determine the actual flow rate from the hydrants or minimise pipe sizes using FHC's auto pipe size command.
