What is directly supported, and what depends on local policy

The following is directly stated by OSHA, DOT/PHMSA, CGA, and institutional EHS sources: the visual cylinder-inspection points and the requirement to follow CGA/DOT inspection guidance; the securement, valve-closure, and cart-only movement rules for cylinders; the 20-foot (or barrier) oxidizer/fuel-gas separation; the 19.5% and 23.5% oxygen deficiency and enrichment thresholds; the instruction never to store a cryogen sealed above its boiling point; the OSHA and CO2 exposure-limit figures; the DOT marking requirements for dry-ice and Category B shipments; and the rewarming guidance for a frostbite or cryogenic-burn exposure. CAP's Laboratory General Checklist separately requires that compressed gas cylinders be secured against falling and that flammable gas cylinders be stored properly.

No specific numeric safe quantity of dry ice for a room or vehicle is stated here; local quantity and ventilation assessment controls use. Cryogens can displace oxygen and, when trapped in a sealed container, build pressure that can rupture it; no precise expansion ratio is given here.

Several items depend entirely on local policy and are not standardized here: the exact make, model, sensor placement, and alarm setpoints of a given facility's oxygen monitor; whether a specific room is formally designated a permit-required confined space; mechanical ventilation design and exhaust rates; the specific securement method and inspection documentation a site uses; the exact segregation layout implementing the 20-foot/barrier rule; the chain of notification and who is authorized to re-enter after an alarm; specific cryoglove, apron, and face-shield product ratings; whether CO2 monitoring, not just O2 monitoring, is deployed in dry-ice spaces; and institutional policy on cryovial cap type and passive-warming procedure. Applying this at a specific site means following that site's written procedure for each of these, not a fixed number.

The CAP checklist references above (for cylinder securement and flammable gas storage) come from one reviewed checklist edition; CAP periodically revises checklist numbering, so a reader should confirm the current item number against the current checklist edition rather than treat these numbers as fixed.

Pressure, extreme cold, and displaced oxygen are hazards a person often cannot feel coming, so the durable habit is to trust the label, the monitor, and the written procedure over a visual impression of the room, the cylinder, or the vial.