No replies to this topic

[arundhamodharan]

I've been thinking about a problem that comes up when working with older pump data: you have a manufacturer's performance curve from an old project, catalogue, or paper document, but the original digital data is no longer available — and sometimes the OEM product line itself is no longer active.  

The curve may still be perfectly useful, but you're left with a scanned or paper Q-H curve rather than a digital dataset.

Curious how others here deal with this:

• Do you digitize the curve manually and recreate the Q-H data in Excel or another tool?

• How do you handle interpolation between the published points?

• When the operating conditions change, how do you generate a revised curve using speed or impeller diameter changes?

• For old curves, how do you handle efficiency and NPSHr data when only the original plotted curves are available?

• For pumps in series or parallel, do you digitize and combine the curves yourself?

I've ended up building an Excel workbook for my own work that takes a pump performance curve from a paper/PDF/image source, converts it into a usable digital curve, and then allows the curve to be evaluated under changed operating conditions using the relevant scaling relationships. It also allows the resulting performance data to be generated in a usable engineering format.

The reason I built it was mainly to make older or otherwise inaccessible pump curves usable again — particularly where the original OEM digital selection software or product database is no longer available.

Happy to share what I developed if anyone is interested. I'm mainly interested in how others here approach this problem and whether there are established methods or tools that you use.