quiostion on performance test tolerances of API-610 1

[rashaa]

Dear all
according to the Table 14 of API-610, the tolerance of the Power is +4.
there is a note b that state :
Under any combination of the above (cumulative tolerances are not acceptable)
would you mind help me to know about this note?
thanks

 

[1gibson]

If you are high in head, you can still only use the + power tolerance from the rated head.

Also, that is from 10th edition, current standard is 11th edition.

 

[rashaa]

Dear 1gibson
would you mind explain more clearly?
why this note was added in API?
could the acceptance of the performance test change without considering this note?
thank you

 

[1gibson]

It is to prevent someone from arguing "I'm 2% high in head, so that should make my power 1.5% higher than rated. Since my power is 5% high from the rated point but only 3.5% high from the +2% head point, it meets the tolerance."

This would not be acceptable.