The moisture content in recycled R-134a that is intended to be returned to an MVAC cannot exceed how many PPM by weight?

The correct answer is 50 PPM by weight for moisture content in recycled R-134a that is intended to be returned to a Motor Vehicle Air Conditioning (MVAC) system. Achieving this standard is crucial because moisture can significantly impede the efficiency and effectiveness of refrigerants in cooling systems. Excess moisture can lead to the formation of acids and sludge, causing corrosion and damage to the components of the AC system. Limiting moisture content to 50 PPM ensures that the recycled refrigerant is suitable for safe use in vehicles, maintaining both performance and the longevity of the system. It balances the need for effective cooling while minimizing potential harmful chemical reactions that can occur with elevated moisture levels.

The other moisture content thresholds are either too low or too high for practical application in MVAC systems, hence they are not deemed appropriate.