I have no argument. I simply mean to state that there is no difference in the physical value that "NPSHr" or "NPSHa" represent, the "r" or "a" being added only to clarify whether one is actually talking about the NPSH that is available, or if one is talking about the NPSH that is required by the pump. The only practical difference is that NPSHa can be calculated, while NPSHr is usually determined by test, although it can also be calculated (or estimated, if you prefer) from correlations to a given pump's specific suction speed.
I think you understand that there is no real difference to NPSH/a or /r, so I'm wondering what your intent is when you say, "BigInch An interesting thread but it really discusses NPSHR not NPSHA as pointed out half way through the posts."
As far as that thread goes, I think it more than adequately discusses calculation of NPSH (and specifically for a vertical can pump),so no further clarification was needed and I didn't see the use in restating what would be already apparent to those reading that thread. If you are critisizing that thread as being irrelevant, I could say that the McNally reference you mention afterward, while it as others on that site are, really excellent references, does not discuss any particularities of calculating NPSH for vertical can pumps.
So, as you are not the OP, who I presume is satisfied by the discussion up to the end of my thread reference, I'm a bit confused as to where are you trying to go with continuation of this apparently finished theread? Do you really have any further questions about NPSH for canned pumps or what?
