Should the pump’s net positive suction head be filled in?
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During the basic design phase of a project, the process engineering team submitted a pump data sheet in which the net positive suction head available for the pumps was not specified. When asked for that value, it was said that it wasn’t important at this stage, as the requirements outlined in the tender were already sufficient. Does the pump’s net positive suction head have little impact on cost? Especially for pumps with a low net positive suction head?
Yes, pumps that require a high net positive suction head will have a much higher cost
If the net positive suction head is not taken into account during the basic design, it may be impossible for this pump to function at all. And as mentioned above, pumps with low cavitation may require higher capital investment. Unless it is obvious that this pump will not experience cavitation, in which case a preliminary estimate is still required.
Is it in the Process Package Date sheet? Generally, important pumps are available, right?~
No, they said that in the later stages of the project, once information on pump levels, tank truck levels, tank levels, as well as pipeline valves is available, the process system and piping specialists will carry out the calculations to determine everything.
Even for basic design, there are corresponding preliminary layout drawings available to estimate the cavitation margin.
During the preliminary stage, an estimated or empirical value is usually used, which is then determined through calculations during the detailed design phase.
The net positive suction head of a pump is one of the most important parameters listed in its data sheet, and it is also a key factor affecting the cost of the pump! Generally, at the BEP stage, hydraulic calculations are first carried out in a conservative manner based on the layout plan, to determine the net positive suction head available and the head required by the pump. It is important to note that the value calculated is the effective net positive suction head available, NPSHa; this value should be entered in the data sheet. After the manufacturer is contacted for a quote, they will provide the minimum net positive suction head required by them. If, during your evaluation, you find that NPSHa – NPSHr > 0.5 m, then it is acceptable. During the DED phase, if there are no significant changes in the layout, hydraulic calculations do not need to be performed again! However, if the installation height of the pump changes, it is necessary to recalculate, determine new process parameters, and submit them to the manufacturer again for a new quote.
They’re talking nonsense; the date sheet should be determined first. The vehicles, pipelines, and valves are determined later. Only 60% of the detailed design for the pipe has been finalized; when will its NPSHr be determined? The date sheet should be determined at 90% completion of the preliminary design, and it serves as basic information at the start of the detailed design.
The project is not large, and its operation process is not very formal; every step that can be omitted is skipped, and many of the intermediate files have defects.