EPA 608 Recovery Cylinder Rules

The 80% fill limit

Recovery equipment must provide overfill protection so that a storage container's liquid fill does not exceed 80% of the tank's rated volume at 21.1 °C (70 °F), per DOT standards (49 CFR §173.304) as referenced in the Part 82 equipment appendices. The headroom is for thermal expansion: liquid refrigerant expands as it warms, and a liquid-full cylinder has nowhere for that expansion to go.

• Fill by weight, on a scale — you cannot judge 80% by pressure, because pressure in a cylinder with liquid present follows temperature, not fill level.
• The limit is volume, not a round weight. The same cylinder's legal refrigerant weight differs by refrigerant, because refrigerants differ in liquid density. Check the cylinder's rating for the refrigerant you are recovering.
• Overfill protection is part of the equipment standard, not an optional accessory: certified recovery equipment must be built to prevent overcharging the storage tank, with a shutoff device and a mechanical pressure relief valve.

DOT ratings, markings, and retesting

Portable refillable tanks used with recovery equipment must meet applicable Department of Transportation (DOT) or Underwriters Laboratories (UL) standards (Part 82 equipment appendices). In the field that means:

• Read the stamping. The cylinder's stamped DOT specification and service pressure tell you whether it is rated for the refrigerant you are about to put in it. A cylinder rated for a lower-pressure refrigerant is not a substitute for one rated for a high-pressure refrigerant.
• Check the retest marking. The tank assembly must be marked with its first retest date — 5 years after the date of manufacture — and retest must be performed every subsequent 5 years. A cylinder past its retest date must not be refilled or transported until it is retested.
• Beware counterfeits. Non-compliant and counterfeit cylinders have reached the market; a cylinder without genuine DOT markings and a verifiable retest history is not a bargain, it is a hazard. Buy from reputable suppliers.
• Valves and relief devices are standardized too. Cylinder valves must comply with UL 1769 and pressure relief devices with CGA Pamphlet S-1.1 under the same equipment appendices.

Labeling: what goes on the cylinder

When a cylinder containing used refrigerant is shipped or sent for reclamation, DOT labeling must identify the refrigerant inside. Labeling serves three purposes the exam likes to ask about: it prevents accidental mixing, it lets the reclaimer identify the contents, and it supports the recordkeeping the rules require. As a working habit, label at the moment of recovery — not when the truck is loaded — with at least the refrigerant type.

Color is a convention, not the label. Recovery cylinders are conventionally gray with a yellow top, which distinguishes them from virgin-refrigerant cylinders (whose colors vary by refrigerant). Color helps you grab the right cylinder; the written label is what the shipment and the reclaimer rely on. A2L cylinders add their own scheme — gray body with a red band marking a flammable refrigerant — covered on the safety-classes page.

Never mix refrigerants in one cylinder

One refrigerant per recovery cylinder, no exceptions in the field. A mixed charge cannot be separated by ordinary recovery or recycling equipment, so it generally cannot be reclaimed and becomes destruction-only material. That is also why recovered refrigerant may be returned, without recycling or reclaiming, only to the appliance it came from or to another appliance owned by the same person (§82.156(h)) — the rule assumes the refrigerant's identity is known and unmixed.

• Recovering a second refrigerant? Get a second, empty, labeled cylinder.
• Unsure what is already in a cylinder? Do not top it off — an unidentified cylinder is a disposal problem, not a storage solution.
• The same discipline applies to hoses and gauges: cross-contamination starts before the cylinder, so A2L work in particular uses dedicated or clearly separated hose sets.

Storage and transport habits

• Upright, secured, capped when not in use — industry practice, and for A2L cylinders it keeps the pressure relief valve in the vapor space.
• Never apply direct heat or an open flame to a cylinder to raise pressure or speed a transfer.
• Full and empty stored separately, away from heat and ignition sources, so nobody grabs a full cylinder thinking it is empty (or the reverse).
• Disposable (DOT-39) cylinders are single-use — never refill one; empty it to zero pressure and render it unusable before disposal. (Industry and exam practice; the refillable-cylinder rules above are the CFR-backed ones.)