Calculation of water pump head
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The head of a water pump can be calculated by adding the total resistance loss in the inlet pipeline, the total resistance loss in the outlet pipeline, and the sum of the elevation difference and pressure difference. The total losses in the inlet and outlet pipelines include the losses associated with elbows, valves, tees, and so on. But how should one calculate the friction loss along the inlet and outlet pipelines? Is it like in the figure below? But the results differ greatly depending on the value of λ; how should this be calculated?
λ is to be obtained from a chart, based on the Reynolds number and the absolute friction coefficient of the pipe.
I’ve seen similar small software programs, but there are still significant differences. So, normally, isn’t the head calculation for water pumps done using this method?
“The pump head can be calculated using: total resistance loss in the inlet pipeline + total resistance loss in the outlet pipeline + the sum of the head difference and pressure difference”~~~~~Who said that?» ?
Yes, it’s all calculated in this way. The initial value of λ can be set a bit higher, as corrosion and scaling inside the pipeline both increase pipe losses.
For ordinary seamless steel pipes, what amount is appropriate?
In a book, several calculation examples are listed in formula form; this written explanation is my translation of those formulas, and I assure you that the translation is correct. How did you do the calculations?
Strictly speaking, it’s not calculated this way; the pressure difference of the equipment for import and export also needs to be taken into account: lol
Both the pressure difference and the head difference are taken into account; the pressure in the container before the pump and the pressure in the container after the pump are provided, and then this pressure difference is converted into head
λ is the resistance coefficient of the pipeline. As for valves, elbows, etc., the equivalent length method can be used, that is, by increasing the value of l in the formula. For example, a valve is equivalent to the resistance of a 10M long pipeline.