All the operations on HVAC are related to fluids. Basically, mechanical installations use air and water. Refrigerants, water vapor, oil and many other fluids are also used in mechanical installations. The most important factor in flow calculations in HVAC systems is the calculation of fluid pressure losses. The fact that the formulas are difficult and iterative causes these calculations to be made on the diagrams. The problem with diagrams related to fluid pressure loss is that these diagrams are logarithmic. It is difficult to read, sometimes it can also cause the wrong values to be read.