The fittings can be selected from the database or the user can enter manually the values of loss coefficient or flow coefficient.
The calculation of the pressure drop in a pipe, including the so-called minor losses or losses in fittings , usually involves a number of estimations, as all the required information is often not available at the moment of design, at least accurately. For example, the flow rate is often not known with accuracy when designing an installation as it depends on the operating point of the pump , pressure loss in the installation and the actual pump curve that finally will be installed . In addition , there are elements that produce a variable pressure loss, not only valves , but also others like filters whose head loss depends on the level of clogging. This is just an example to highlight the difficulty of accurately estimating many parameters of the system and that it is important to have a tool to make a quick assessment of up to what extent these inaccuracies can be really relevant.
The following chart shows how the pipe diameter affects the pressure drop:
Using the above curves, the pipe diameter can be sectected inmediately. The curves show that the main cause of the pressure difference between the inlet and outlet of the installation is due to the loss in straight runs (blue curve). The head loss in fittings (black curve) is small and varies slightly when changing the diameter. Yellow curve is due to the difference in height between the inlet and outlet and has a constant value equal to the difference of the liquid column.
In the following example the pressure loss is shown against variations of flow rate:
Our recommendation is that if it is possible you should enter into the LFlow application the K , Kv or Cv values provided by the manufacturers as this is the way to get more accurate values. However, this information sometimes is not available for many fittings as elbows , reducers , tees, etc., so it will have to be used the database. The database calculates the loss coefficient for the selected diameter. Using this fittings database has an important advantage, that is the possibility of obtaining a graph showing how the pressure loss changes for different diameters. This is of great interest when designing the installation as it helps for the selection of the diameter of the line. It should be taken as an estimatation since these values have been determined empirically and reflected in different literature and standards, but because of its dependence on factors such as the exact geometry of the element and its diameter, different sources show different values for the same type of fitting. However, as mentioned earlier, in many cases these losses may even be negligible, especially for very long pipes with relatively few accessories. In these cases , the uncertainty introduced will not be relevant.
In practice, most of the installations work with turbulent flows.
L Flow can show a chart for pressure drop as a function of flow rate. This chart includes curves for pressure loss in straight pipe run, pressure loss in fittings and difference in pressure due to elevation. You can compare this curves with the pump curve to see the actual operating point
Yes, the software allow the user for most of the paramenters to select between different engineering units.
Yes, all the reports show a button for printing.
Yes, do not hesitate to contact us and let us know your requirments.
You will need to have installed .NET Framework 4 from Microsoft o any compatible version. This software comes installed by default with Vista, Windows7, Windows8 and sometimes with Windows XP. In case it is not already installed you can download it for free from the Microsoft website.
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