API 650 app P figure P.4a logaritmic scale

[cornemo]

I have a question regarding API 650 appendix P figures P.4a and P.4b.
These figures tend to be log-log graphs based on the numeric scale given on both axis.

However both axis in figure P.4a have a numbered scale which is logaritmic, but has intermediate scales which are linear.
How to deal with this?
option 1: use the scale as indicated in the figure, for example for lambda = 0.75, get in the middle between 0.5 and 1.0.
option 2: disregard the given scale and, for example for lambda = 0.75, get more towards 1.0 assuming a pure logaritmic scale.

Your opinions are appreciated.

 

[cornemo]

No opinions on this matter?

 

[JStephen]

I don't often get involved with nozzle load calcs, but have observed the same thing. In particular, noted that you have curve A, B, and C, and if you interpolate between A and C, you don't get B, so therefore, not a lot of confidence that interpolating between A and B gives much precision, either.

One thing I would suggest is to see if you can get copies of the technical papers that Annex P was based on, to see if they shed any light on it.