Necessity and Technical Analysis of Purging in Constant Temperature and Humidity Air Conditioning Refrigeration Systems

Purging the refrigeration system of constant temperature and humidity air conditioners is a critical maintenance measure to ensure long-term stable operation. Its necessity is primarily reflected in the following six core dimensions:

1. Sources and Hazards of Contaminants

2. Core Benefits of Purging

1. Energy Efficiency Assurance

• A 1mm-thick oil film can raise evaporation temperature by 2-3°C, reducing cooling capacity by 10-15%

• Case: A data center that neglected regular purging saw COP drop from 3.2 to 2.6 over 3 years

2. Extended Equipment Lifespan

• Timely removal of acidic substances can extend compressor life from 5 to 10 years

• ASHRAE standards recommend purging every 2 years or 10,000 operating hours

3. Precision in Temperature and Humidity Control

• Temperature fluctuations > ±1°C (exceeding Class A机房 standards)

• Humidity deviations > ±5%RH

• Contaminants interfere with electronic expansion valve operation, causing:

3. Purging Technical Solutions

1. Physical Purging Methods

• Install molecular sieve filters (3Å pores adsorb moisture and acidic substances)

• Use 40-60bar nitrogen for sectional purging (main pipeline → capillary tubes)

• Requirement: Nitrogen dew point ≤ -40°C (to prevent reintroducing moisture)

• High-Pressure Nitrogen Blowing:

• Filter Adsorption:

2. Chemical Treatment Methods

• Circulate solvents like RJ-11 for 2-4 hours to dissolve oil sludge

• Replace dryer filters post-cleaning (typically with 5-10μm mesh)

• Online Cleaning Agents:

3. Smart Monitoring Methods

• Oil quality sensors: Monitor refrigeration oil acidity in real-time (>1.5mgKOH/g requires treatment)

• Particle counters: Detect particles in oil return lines (NAS 1638 Class 6 is acceptable)

4. Standard Purging Process

Key Parameter Controls:

• Purging gas flow velocity: ≥15m/s (ensures removal of deposits)

• Vacuum hold test: Pressure rise ≤0.5kPa over 24 hours

5. Industry Standards

1. Chinese National Standard GB/T19413

• Moisture ≤100ppm

• Acid value ≤0.5mgKOH/g

• Specifies contaminant limits in refrigeration systems:

2. ASHRAE Guideline 3

• Recommends post-purging refrigerant purity ≥99.8%

• Residual non-condensable gases ≤1.5%

6. Typical Failures Due to Neglected Purging

• Case Study: A Semiconductor Factory

• Failure to purge led to:

1. Electronic expansion valve jamming (replacement cost: $2,800)

2. Compressor winding corrosion and short-circuit (repair cost: $15,000)

3. Annual excess power consumption of 180,000 kWh (loss: $25,000)

Conclusion:
 Purging the refrigeration system of constant temperature and humidity air conditioners is not an "optional maintenance task" but a necessary measure directly impacting equipment reliability, energy efficiency, and precision. Adopting a "preventive maintenance + smart monitoring" strategy can reduce system failure rates by over 60%. It is recommended to establish customized purging cycles (typically every 2 years or 8,000 operating hours) based on equipment logs.

Necessity and Technical Analysis of Purging in Constant Temperature and Humidity Air Conditioning Refrigeration Systems

Purging the refrigeration system of constant temperature and humidity air conditioners is a critical maintenance measure to ensure long-term stable operation. Its necessity is primarily reflected in the following six core dimensions:

1. Sources and Hazards of Contaminants

2. Core Benefits of Purging

1. Energy Efficiency Assurance

• A 1mm-thick oil film can raise evaporation temperature by 2-3°C, reducing cooling capacity by 10-15%

• Case: A data center that neglected regular purging saw COP drop from 3.2 to 2.6 over 3 years

2. Extended Equipment Lifespan

• Timely removal of acidic substances can extend compressor life from 5 to 10 years

• ASHRAE standards recommend purging every 2 years or 10,000 operating hours

3. Precision in Temperature and Humidity Control

• Temperature fluctuations > ±1°C (exceeding Class A机房 standards)

• Humidity deviations > ±5%RH

• Contaminants interfere with electronic expansion valve operation, causing:

3. Purging Technical Solutions

1. Physical Purging Methods

• Install molecular sieve filters (3Å pores adsorb moisture and acidic substances)

• Use 40-60bar nitrogen for sectional purging (main pipeline → capillary tubes)

• Requirement: Nitrogen dew point ≤ -40°C (to prevent reintroducing moisture)

• High-Pressure Nitrogen Blowing:

• Filter Adsorption:

2. Chemical Treatment Methods

• Circulate solvents like RJ-11 for 2-4 hours to dissolve oil sludge

• Replace dryer filters post-cleaning (typically with 5-10μm mesh)

• Online Cleaning Agents:

3. Smart Monitoring Methods

• Oil quality sensors: Monitor refrigeration oil acidity in real-time (>1.5mgKOH/g requires treatment)

• Particle counters: Detect particles in oil return lines (NAS 1638 Class 6 is acceptable)

4. Standard Purging Process

A[System Shutdown and Depressurization] --> B[Remove Dryer Filter]    B --> C[High-Pressure Nitrogen Sectional Blowing]    C --> D[Replace Refrigeration Oil]    D --> E[Evacuate to ≤500Pa]    E --> F[Recharge with New Refrigerant]    F --> G[Operational Testing]

Key Parameter Controls:

• Purging gas flow velocity: ≥15m/s (ensures removal of deposits)

• Vacuum hold test: Pressure rise ≤0.5kPa over 24 hours

5. Industry Standards

1. Chinese National Standard GB/T19413

• Moisture ≤100ppm

• Acid value ≤0.5mgKOH/g

• Specifies contaminant limits in refrigeration systems:

2. ASHRAE Guideline 3

• Recommends post-purging refrigerant purity ≥99.8%

• Residual non-condensable gases ≤1.5%

6. Typical Failures Due to Neglected Purging

• Case Study: A Semiconductor Factory

• Failure to purge led to:

1. Electronic expansion valve jamming (replacement cost: $2,800)

2. Compressor winding corrosion and short-circuit (repair cost: $15,000)

3. Annual excess power consumption of 180,000 kWh (loss: $25,000)

Conclusion:
 Purging the refrigeration system of constant temperature and humidity air conditioners is not an "optional maintenance task" but a necessary measure directly impacting equipment reliability, energy efficiency, and precision. Adopting a "preventive maintenance + smart monitoring" strategy can reduce system failure rates by over 60%. It is recommended to establish customized purging cycles (typically every 2 years or 8,000 operating hours) based on equipment logs.