When describing allowable leakage, the standard refers to ".01% of rated valve capacity". Rated valve capacity is defined as "the quantity of test fluid that would pass through the valve at rated travel under the stated pressure conditions as defined by the appropriate equations and manufacturers ratings."This reads like something the government would come up with. We want to quantify allowable leakage for a metal/metal seated ball valve to meet Class IV. If I assume (yes, I know the repurcussions of that..) that "rated valve capacity" is Cv, then I can have .01% of Cv/min. and meet Class IV.Can anyone help me with this one ? Gratitude is given in advance. Yes, that is how I've interpreted it also. for me too, if not specified otherwise, "valve rated travel" means the valve 100% open. Just for information, I add that sometimes Customer specifications require FCI 70-2 tightness classes in conditions very different from the standard ones for which classes are defined (typically for cryogenic valves and then -196