CFR › Title 21 › Part 864 › §864.595021 CFR §864.5950Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy link(a)Identification. A blood volume measuring device is a manual, semiautomated, or automated system that is used to calculate the red cell mass, plasma volume, and total blood volume.(b)Classification. Class II (performance standards).