EPA 608 609 Study Guide 2026

Hydrogen is a highly flammable gas that can form explosive mixtures with air. If vented in a closed environment, it can accumulate and pose a significant explosion hazard when exposed to an ignition source. Therefore, extreme caution must be exercised when handling or venting hydrogen to prevent dangerous incidents.

Adding refrigerant to a leaking system wastes it and contributes to prohibited emissions.

A star after the retest date means the cylinder passed an enhanced test and is approved for a 10-year requalification interval instead of the standard 5 years.

High-pressure appliances with a working compressor must be evacuated to 10 inches of mercury vacuum with post-1993 recovery equipment.

Oxygen can combine with oil and cause a violent explosion.

If refrigerant is recovered from a system and stored in a refillable cylinder, it can typically be charged back into the *same* system after repairs, provided it has not been contaminated. EPA regulations allow for reuse of recovered refrigerant by the same technician in the same system without requiring reclamation. However, if the refrigerant is transferred to another system or another owner, it must be reclaimed to meet purity standards.