Limiting characteristics/quality verification levels

Table 1, from CGA G-1.1, Commodity Specification for Acetylene, presents component maxima in parts per million, ppm (mole/mole) unless otherwise shown, for the grades (also denoted as quality verification levels) of acetylene [2]. A blank indicates no maximum limiting characteristic. The absence of a listed value in a quality verification level does not mean to imply that the limiting characteristic is or is not present, but merely indicates that the test is not required for compliance with the specification. 

Table 1. Directory of Limiting Characteristics (Units in ppm (v/v) Unless Shown Otherwise) Quality Verification Levels (grades)...

Table 1 from CGA G-5.3, Commodity Specification for Hydrogen, presents the component maxima in parts per million (v/v), unless shown otherwise, for the types and grades of hydrogen [I]. These are also known as quality verification levels (QVLs). Gaseous hydrogen is denoted as Type I, and liquefied hydrogen as Type II in the table. A blank indicates no maximum limiting characteristics are specified. 

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