Refrigerant Recycling Procedures and Standards

Refrigerant recycling is the process of extracting contaminated refrigerant from HVAC systems and restoring it to acceptable purity levels through filtration and separation processes. On-site recycling reduces material costs, minimizes environmental impact, and enables immediate system recharging with cleaned refrigerant.

ARI 740 Recycling Standards

The Air-Conditioning, Heating, and Refrigeration Institute (ARI) Standard 740 defines the minimum performance requirements for refrigerant recycling equipment. This standard ensures recycled refrigerant meets specific purity criteria for safe reuse.

Purity Requirements

ARI 740 equipment must demonstrate the ability to consistently achieve these purity levels across multiple test cycles using contaminated refrigerant samples.

On-Site Recycling Equipment

Modern recycling machines integrate three primary contamination removal systems into portable units weighing 40-80 lbs for field service applications.

Core Components

Oil Separator

• Centrifugal or coalescing filter design
• Removes 80-95% of entrained compressor oil
• Operating pressure: 150-300 psig
• Separator efficiency depends on refrigerant velocity and temperature

Filter-Drier Assembly

• Replaceable core containing molecular sieve desiccant
• Removes moisture, acids, and solid particulates
• Typical capacity: 16-32 oz desiccant per cartridge
• Replace when moisture breakthrough occurs (indicator change)

Air Purge System

• Automated or manual non-condensable gas venting
• Operates when machine reaches thermal equilibrium
• Purges from high side while refrigerant is in liquid phase
• Pressure differential indicates presence of air (>10 psi above saturation)

Recycling Process Workflow

flowchart TD
    A[Connect Recovery Cylinder] --> B[System Evacuation]
    B --> C[Refrigerant Transfer to Machine]
    C --> D[Oil Separation Chamber]
    D --> E{Oil Level Check}
    E -->|High| F[Drain Oil Reservoir]
    E -->|Normal| G[Pass to Filter-Drier]
    F --> G
    G --> H[Moisture & Acid Removal]
    H --> I[Storage Tank Internal]
    I --> J{Pressure Test}
    J -->|Non-condensables Present| K[Air Purge Cycle]
    J -->|Clean| L[Transfer to Clean Cylinder]
    K --> M[Retest Pressure]
    M --> L
    L --> N[Label & Date Cylinder]
    N --> O[Ready for Reuse]

Oil Separation Process

Lubricating oil circulates through HVAC systems and mixes with refrigerant, creating a contamination that reduces heat transfer efficiency and clogs expansion devices.

Separation Methods

Gravity Separation

• Relies on density difference between oil and refrigerant
• Requires 10-30 minutes residence time in separator vessel
• Effective for oil concentrations above 5% by weight
• Temperature maintained at 70-90°F for optimal separation

Centrifugal Separation

• Uses rotating impeller to generate 500-2000 G forces
• Separates oil droplets as small as 1 micron
• Processing rate: 1-3 lbs refrigerant per minute
• More effective for POE and PVE synthetic oils

Oil drained from separators contains 10-30% dissolved refrigerant. Allow drained oil to de-gas in open container for 24 hours before disposal or reclamation.

Moisture Removal Process

Water contamination causes acid formation, copper plating, and ice blockages in expansion devices. Recycling machines use molecular sieve desiccants to achieve moisture levels below 50 ppm.

Desiccant Performance

Replace filter-drier cores when:

• Moisture indicator shows saturation (color change)
• Processing time doubles from baseline
• Outlet moisture levels exceed 50 ppm
• After recycling 200-400 lbs refrigerant (manufacturer specification)

Acid Removal Process

Acids form when moisture reacts with refrigerant breakdown products or POE lubricants. Hydrochloric acid (HCl) and hydrofluoric acid (HF) corrode copper and aluminum components.

Removal Mechanisms

Activated Alumina Adsorption

• Surface area: 200-300 m²/g
• Removes organic and inorganic acids
• Capacity: 0.5-2% by weight acid
• Indicated by pH test strips (target pH 6-8)

Molecular Sieve Interaction

• Secondary acid removal through ion exchange
• Effective for low concentration polishing (<10 ppm)
• Regeneration releases captured acids

Test recycled refrigerant acid content using pH indicator test strips. Draw 10 ml sample, add pH indicator solution, observe color change. Yellow-green indicates acceptable acid levels (pH 6-8), while red indicates excessive acidity requiring additional filtration.

Equipment Operation Standards

Pre-Operation Checks

1. Verify filter-drier moisture indicator shows dry condition (blue or green)
2. Check oil separator reservoir level (drain if above 50% capacity)
3. Inspect hoses for cracks, verify connections are clean
4. Confirm storage cylinder is evacuated below 500 microns
5. Ensure machine sits level for accurate oil separation

Operating Parameters

Quality Verification

After recycling, verify refrigerant purity:

• Standing pressure test: Compare cylinder pressure to saturation pressure at ambient temperature (within ±10 psi indicates <2% non-condensables)
• Moisture test: Use electronic moisture sensor or indicator (target <50 ppm)
• Visual inspection: Liquid refrigerant should be clear, colorless, free of particles
• Acid test: pH test strips should indicate neutral to slightly alkaline

Label recycled refrigerant cylinders with refrigerant type, recycling date, quantity, and technician identification. Storage time limit is typically 6-12 months before retesting is required.