Spring Strength Specs??

[CDBPDX]

Is there some way to know how much strength a spring has? Some kind of chart or graph that lists minimum foot pounds of torque for a spring of a certain size? And how would one go about testing a spring?

I am pretty fair at eyeballing bad/weak springs, but is there a definitive way to test the strength of a spring to see if it meets certain minimum requirements?

I believe most folks use a judgement call to decide whether to replace or reuse a spring, probably as good a method as any, but do specs exist?

Cliff