Final answer:
Approved refrigerant recovery cylinders can be identified by their label or markings, color-coding, specific markings, and unique valve fittings or connections.
Step-by-step explanation:
Approved refrigerant recovery cylinders can be identified by their label or markings. These cylinders are usually color-coded and have specific markings to indicate that they are designed for refrigerant recovery. For example, cylinders used for hydrochlorofluorocarbons (HCFCs) like HCFC-22, HCFC-123, and HCFC-124 may have a specific label indicating their compatibility with these refrigerants.
Additionally, some refrigerant recovery cylinders may have unique valve fittings or connections that can only be used with specific refrigerants. This helps prevent mixing different refrigerants in the same cylinder, which could lead to contamination or other safety issues.