Proper commissioning directly determines the long-term stability and service life of reciprocating refrigeration compressor, screw refrigeration compressor and cascade refrigeration unit.
Before startup, inspect foundation settlement, anchor bolt tightness, pipe alignment and vibration isolation pads for small, medium, large 4-cylinder and large 6-cylinder reciprocating refrigeration compressor.
Check oil level, oil cleanliness grade and oil type. Reciprocating single-stage units use ISO VG68; single-unit two-stage and cascade low-stage loops require ISO VG100 refrigeration oil.
Verify sensor calibration for evaporation pressure, discharge pressure, bearing temperature and suction superheat. Sensor deviation over 0.05MPa will disrupt system control logic.
Inspect safety relief valve calibration certificate. All relief valves on reciprocating, screw and cascade refrigeration systems must be calibrated annually and sealed properly.
Carry out nitrogen pressure holding test and vacuum dehydration before refrigerant charging. Leakage rate must be controlled to meet the requirement of annual leakage under 0.5%.
For reciprocating refrigeration compressor, crankcase heater must be energized for at least 8 hours before startup to boil off dissolved refrigerant and prevent oil dilution.
Check unloading mechanism function for piston compressors. Confirm 25/50/75% capacity adjustment works normally for 4-cylinder models and multi-step unloading for large 6-cylinder units.
For screw refrigeration compressor, test slide valve movement to confirm smooth stepless capacity adjustment from 10% to 100% without jamming or abnormal noise.
For single-unit two-stage refrigeration compressor, focus on interstage pressure setting to avoid excessive discharge temperature which damages piston and valve plate materials.
For cascade refrigeration unit, commission high-stage and low-stage circuits separately. Check cascade heat exchanger temperature difference controlled within 5K–8K.
After initial startup, monitor suction superheat continuously. Maintain 6K–10K for single-stage reciprocating, 8K–12K for two-stage piston and cascade low-stage circuit.
Check oil pressure differential during running. Normal oil pressure difference: 0.2–0.4MPa for piston compressors, 0.3–0.5MPa for screw refrigeration compressor.
Record operating parameters continuously for 24 hours in acceptance test: suction pressure, discharge pressure, oil temperature, bearing temperature, current and power factor.
Check abnormal vibration and noise. Excessive vibration indicates shaft misalignment, loose anchor bolts or improper pipe stress on compressor flanges.
Check liquid return risk. Any liquid carry-over into compressor will cause liquid hammer and quickly destroy valve plates for reciprocating piston compressors.
Check oil separator performance. Oil carry-over rate higher than 0.5% will contaminate heat exchanger and reduce heat transfer coefficient gradually.
Confirm protection functions: high discharge pressure, high bearing temperature, low oil pressure and overload protection can trigger power cut reliably during fault simulation.
For long-term shutdown over 6 months, perform oil change, filter cleaning and nitrogen sealing to avoid internal rust inside cylinder or rotor chamber.
Record baseline parameters during acceptance, to be compared in later routine inspection for early detection of performance degradation of refrigeration compressor.
System acceptance shall also include operator training on daily inspection, alarm handling and correct startup/shutdown sequence for reciprocating, screw and cascade refrigeration equipment.
Many premature compressor failures are caused by improper commissioning, such as insufficient preheating, wrong oil grade, uncalibrated sensors or poor vacuum treatment.
xiteliduo reciprocating compressor series requires the same commissioning logic for small, medium, large 4-cylinder and large 6-cylinder models, simplifying on-site operation.
Explosion-proof models need extra inspection on flameproof joint clearance and cable sealing during commissioning to meet Ex d II BT4 safety requirements.
Condenser fouling pre-check is required at acceptance. Clean condenser ensures condensing temperature stays within 38–45℃ and avoids capacity loss.
Suction pipe velocity verification is needed to guarantee oil return. Reciprocating:12–18m/s; screw refrigeration compressor suction pipe velocity controlled at 15–22m/s.
Power supply test: verify voltage fluctuation within ±10% rated voltage. Voltage instability will trigger frequent overload protection and damage motor windings.
After commissioning, set up maintenance schedule: filter inspection, oil sampling, valve inspection and sensor recalibration according to different compressor types.
FAQ
Q: How long should crankcase heater be powered before starting reciprocating refrigeration compressor?
A: Minimum 8 hours of preheating to release dissolved refrigerant and prevent oil dilution and liquid hammer risk.
Q: What suction superheat range is recommended for single-stage reciprocating refrigeration compressor?
A: Maintain suction superheat between 6K and 10K for stable operation and liquid return prevention.
Q: How to commission cascade refrigeration unit?
A: Commission high-stage and low-stage refrigerant circuits separately, control cascade heat exchanger temperature difference at 5K–8K.
Q: What oil grade is used for single-unit two-stage refrigeration compressor?
A: ISO VG100 synthetic refrigeration oil matched with low-temperature refrigerant such as R23.
Q: What is the acceptance test requirement for refrigeration compressor?
A: 24-hour continuous running test with full parameter recording, verify all protection functions and pressure holding leak test.
Q: What is the main risk during commissioning of reciprocating piston compressor?
A: Liquid slugging caused by insufficient crankcase preheating and improper suction superheat control.
Q: What inspection items are required for safety relief valve?
A: Conduct annual calibration and keep valid calibration certificate, ensure fast response during pressure spike.
Refrigeration Compressor System Commissioning & Acceptance Checklist for Reciprocating, Screw and Cascade Units
Proper commissioning directly determines the long-term stability and service life of reciprocating refrigeration compressor, screw refrigeration compressor and cascade refrigeration unit. Before startup, inspect foundation settlement, anchor bolt tightness, pipe alignment and vibration isolation pads for small, medium, large 4-cylinder and large 6-cylinder reciprocating refrigeration compressor. Check oil level, oil cleanliness grade and oil type. Reciprocating single-stage units use ISO VG68; single-unit two-stage and cascade low-stage loops require ISO VG100 refrigeration oil. Verify sensor calibration for evaporation pressure, discharge pressure, bearing temperature and suction superheat. Sensor deviation over 0.05MPa will disrupt system control logic. Inspect safety relief valve calibration certificate. All relief valves on reciprocating, screw and cascade refrigeration systems must be calibrated annually and sealed properly. Carry out nitrogen pressure holding test and vacuum dehydration before refrigerant charging. Leakage rate must be controlled to meet the requirement of annual leakage under 0.5%. For reciprocating refrigeration compressor, crankcase heater must be energized for at least 8 hours before startup to boil off dissolved refrigerant and prevent oil dilution. Check unloading mechanism function for piston compressors. Confirm 25/50/75% capacity adjustment works normally for 4-cylinder models and multi-step unloading for large 6-cylinder units. For screw refrigeration compressor, test slide valve movement to confirm smooth stepless capacity adjustment from 10% to 100% without jamming or abnormal noise. For single-unit two-stage refrigeration compressor, focus on interstage pressure setting to avoid excessive discharge temperature which damages piston and valve plate materials. For cascade refrigeration unit, commission high-stage and low-stage circuits separately. Check cascade heat exchanger temperature difference controlled within 5K–8K. After initial startup, monitor suction superheat continuously. Maintain 6K–10K for single-stage reciprocating, 8K–12K for two-stage piston and cascade low-stage circuit. Check oil pressure differential during running. Normal oil pressure difference: 0.2–0.4MPa for piston compressors, 0.3–0.5MPa for screw refrigeration compressor. Record operating parameters continuously for 24 hours in acceptance test: suction pressure, discharge pressure, oil temperature, bearing temperature, current and power factor. Check abnormal vibration and noise. Excessive vibration indicates shaft misalignment, loose anchor bolts or improper pipe stress on compressor flanges. Check liquid return risk. Any liquid carry-over into compressor will cause liquid hammer and quickly destroy valve plates for reciprocating piston compressors. Check oil separator performance. Oil carry-over rate higher than 0.5% will contaminate heat exchanger and reduce heat transfer coefficient gradually. Confirm protection functions: high discharge pressure, high bearing temperature, low oil pressure and overload protection can trigger power cut reliably during fault simulation. For long-term shutdown over 6 months, perform oil change, filter cleaning and nitrogen sealing to avoid internal rust inside cylinder or rotor chamber. Record baseline parameters during acceptance, to be compared in later routine inspection for early detection of performance degradation of refrigeration compressor. System acceptance shall also include operator training on daily inspection, alarm handling and correct startup/shutdown sequence for reciprocating, screw and cascade refrigeration equipment. Many premature compressor failures are caused by improper commissioning, such as insufficient preheating, wrong oil grade, uncalibrated sensors or poor vacuum treatment. xiteliduo reciprocating compressor series requires the same commissioning logic for small, medium, large 4-cylinder and large 6-cylinder models, simplifying on-site operation. Explosion-proof models need extra inspection on flameproof joint clearance and cable sealing during commissioning to meet Ex d II BT4 safety requirements. Condenser fouling pre-check is required at acceptance. Clean condenser ensures condensing temperature stays within 38–45℃ and avoids capacity loss. Suction pipe velocity verification is needed to guarantee oil return. Reciprocating:12–18m/s; screw refrigeration compressor suction pipe velocity controlled at 15–22m/s. Power supply test: verify voltage fluctuation within ±10% rated voltage. Voltage instability will trigger frequent overload protection and damage motor windings. After commissioning, set up maintenance schedule: filter inspection, oil sampling, valve inspection and sensor recalibration according to different compressor types.
FAQ Q: How long should crankcase heater be powered before starting reciprocating refrigeration compressor? A: Minimum 8 hours of preheating to release dissolved refrigerant and prevent oil dilution and liquid hammer risk. Q: What suction superheat range is recommended for single-stage reciprocating refrigeration compressor? A: Maintain suction superheat between 6K and 10K for stable operation and liquid return prevention. Q: How to commission cascade refrigeration unit? A: Commission high-stage and low-stage refrigerant circuits separately, control cascade heat exchanger temperature difference at 5K–8K. Q: What oil grade is used for single-unit two-stage refrigeration compressor? A: ISO VG100 synthetic refrigeration oil matched with low-temperature refrigerant such as R23. Q: What is the acceptance test requirement for refrigeration compressor? A: 24-hour continuous running test with full parameter recording, verify all protection functions and pressure holding leak test. Q: What is the main risk during commissioning of reciprocating piston compressor? A: Liquid slugging caused by insufficient crankcase preheating and improper suction superheat control. Q: What inspection items are required for safety relief valve? A: Conduct annual calibration and keep valid calibration certificate, ensure fast response during pressure spike.
