Hydrocarbon Refrigeration
Hydrocarbon refrigeration compressor lubricants are polyalphaolefin (PAO) or polyalkylene glycol (PAG) fluids engineered for systems that run on propane (R-290), isobutane (R-600a), propylene (R-1270), butane (R-600), and lighter hydrocarbon refrigerants. Hydrocarbon refrigerant dissolves into the compressor lubricant and reduces its operating viscosity. The hydrocarbon, lubricant chemistry, pressure, and temperature set the degree of dilution, which makes refrigerant-lubricant interaction the primary factor in product selection.
NEXT Lubricants produces PAO and PAG formulations for hydrocarbon refrigeration across industrial cooling, process and petrochemical refrigeration, and cascade systems.
- Hydrocarbon refrigerant dissolves into the compressor lubricant and reduces its operating viscosity.
- Heavier, more condensable hydrocarbons cause greater dilution than lighter ones.
- PAO and PAG are the lubricant chemistries for hydrocarbon refrigeration. PAG resists dilution; PAO delivers the lowest-temperature fluidity.
- Hydrocarbon composition, compressor design, pressure, temperature, oil-return requirements, and required operating viscosity determine lubricant selection.
How Hydrocarbon Refrigeration Works and the Compressor's Role
A hydrocarbon refrigeration system removes heat by evaporating a hydrocarbon refrigerant at low pressure. The system rejects that heat after compression and condensation at higher pressure. The refrigerant then passes through an expansion stage and returns to the evaporator.
The compressor raises low-pressure hydrocarbon vapor to the pressure required for condensation and heat rejection. Industrial installations use rotary screw or reciprocating compressors in single-stage, two-stage, economized, or cascade configurations. The refrigerant, system capacity, and target temperature set the configuration.
The lubricant protects bearings, rotors, cylinder walls, and other moving parts. It also seals, cools, and maintains oil-system operation. Hydrocarbon refrigerant dissolves into the lubricant and reduces operating viscosity, so the lubricant holds sufficient in-service viscosity to protect the compressor across the operating envelope.
Petrochemical & Process Refrigeration
Propane and propylene refrigeration are extensively used in petrochemical plants, refineries, and LPG facilities for process cooling, fractionation, and low-temperature hydrocarbon separation.
Industrial Cold Storage & Food Processing
Propane and other hydrocarbon refrigerants are utilized in industrial refrigeration systems for cold storage, freezing, food processing, and beverage production.
Chemical & Manufacturing Processes
Hydrocarbon refrigeration is also employed for process cooling in chemical and manufacturing settings where propane, butane, isobutane, or similar refrigerants are suitable for the required temperature range.
Cascade & Low-Temperature Refrigeration
Hydrocarbon refrigerants are used in cascade systems where different refrigerants operate at various temperature levels to achieve low evaporating temperatures.
Lubrication Considerations for Hydrocarbon Refrigeration
Hydrocarbon refrigeration imposes different lubricant demands than HFC, HFO, ammonia, and CO₂ systems. The primary factors are refrigerant dilution, hydrocarbon type and condensability, operating conditions, oil return, and material compatibility.
Refrigerant Dilution and Operating Viscosity
Hydrocarbon refrigerant dissolves into the lubricant during operation and reduces the viscosity of the lubricant-refrigerant mixture. Lower viscosity reduces film thickness inside the compressor. The hydrocarbon, lubricant chemistry, pressure, and oil temperature set the degree of dilution.
The extent of dilution is contingent upon the hydrocarbon, lubricant chemistry, pressure, and oil temperature. Selection should be based on expected in-service viscosity rather than the fresh-oil ISO grade alone.
Hydrocarbon Type and Condensability
Propane, isobutane, butane, propylene, and lighter hydrocarbon refrigerants interact differently with the lubricant. Heavier, more condensable hydrocarbons cause greater dilution, particularly near the dew point or when liquid refrigerant enters the compressor. Separation and system control handle continuous liquid carry-over; lubricant selection does not offset it.
Oil Return and Low-Temperature Performance
The lubricant holds fluidity and circulation across the low-temperature side of the system. Refrigerant-lubricant interaction governs oil return, and excessive dilution reduces operating viscosity and film strength inside the compressor. Pour point, low-temperature viscosity, and system design determine oil return together. NEXT PAO reaches a pour point of -68 °C for low-temperature and cryogenic hydrocarbon service.
Operating Conditions Affecting Lubricant Selection
Lubricant selection depends on the complete operating conditions of the hydrocarbon refrigeration system. The nominal ISO viscosity grade does not indicate how the lubricant will perform after refrigerant dilution.
- Hydrocarbon Composition Determines refrigerant solubility, dilution severity, and the lubricant properties required to maintain operating viscosity.
- Suction and Discharge Conditions Influence refrigerant concentration in the oil, pressure ratio, compressor loading, and discharge temperature
- Evaporating and Low-Side Temperature Determine low-temperature fluidity, oil return and refrigerant circulation.
- Oil Temperature and Dilution Affect the amount of hydrocarbon retained in the lubricant and the resulting viscosity inside the compressor.
Operational Benefits of Correct Ammonia Lubricant Selection
Selecting the lubricant according to the hydrocarbon refrigerant, compressor and operating conditions can provide several operational benefits.
- Stable Operating Viscosity Maintains film strength after hydrocarbon refrigerant dilutes the lubricant.
- Reliable Oil Return and Lower Consumption Maintains oil circulation and reduces carryover, lubricant loss and top-up frequency.
- Clean Running and Deposit Control Limits varnish, sludge and deposit formation and keeps oil circulation reliable.
- Reduced Unplanned Downtime Prevents lubrication-related wear, overheating, oil-return failures and unplanned compressor shutdowns.
- Extended Component Life Protects bearings, rotors, cylinders, seals and other lubricated compressor components.
- Consistent Compressor Efficiency Maintains sealing and lubrication without adding viscous drag.
Hydrocarbon Refrigeration Compressor Lubricants
NEXT PAO
Ethane/Methane/Ethylene Refrigeration Lubricant
Base Oil: PAO
ISO Range: 15 – 320
NEXT GPL PAG
Propane/ Light Hydrocarbon Refrigeration Lubricant
Base Oil: PAG
ISO Range: 32 – 680
NEXT GPL PAG-WS
Propane/ Heavy Hydrocarbon Refrigeration Lubricant
Base Oil: PAG (EO/PO)
ISO Range: 32 – 320
Our technical team can help identify the right product.
Lubricant Selection, Technical Support and Compatibility Documentation
NEXT combines application knowledge, laboratory data and an extensive internal cross-reference database to support lubricant selection, conversions and compressor troubleshooting.
Depending on the application, we can provide:
- Application-Specific Product Recommendations Lubricant recommendations based on gas or refrigerant composition, compressor design, operating conditions and current performance issues.
- Lubricant Cross-Referencing Identifies suitable NEXT alternatives by comparing base-oil chemistry, viscosity, application, specifications and operating requirements.
- Compatibility and Conversion Documentation Provides chemistry comparisons, mixture-test data, material compatibility, flushing requirements and top-off or changeover guidance.
- Dilution Data and PVT Graphs Shows how gas or refrigerant concentration, pressure and temperature affect lubricant dilution, density and operating viscosity.
- Troubleshooting and Root-Cause Support Supports investigations into foaming, oil carryover, dilution, deposits, corrosion, high lubricant consumption and reduced oil life.
What type of oil is used in hydrocarbon refrigeration compressors?
Why do hydrocarbon refrigerants reduce compressor oil viscosity?
Hydrocarbon refrigerants can dissolve into the lubricant during operation. Dissolved refrigerant reduces the viscosity of the oil-refrigerant mixture, with the degree of dilution depending on lubricant chemistry, pressure and temperature. The lubricant should therefore be selected according to expected in-service viscosity rather than fresh-oil viscosity alone.
What is the difference between PAO and PAG for hydrocarbon refrigeration?
What is the difference between NEXT GPL PAG and NEXT GPL PAG-WS?
Can I use PAO in a propane refrigeration system?
Explore Other Refrigeration Applications
CO₂ Refrigeration
Lubricants for R744 transcritical, subcritical and cascade refrigeration systems.
Ammonia Refrigeration
Lubricants for large-scale industrial R717 refrigeration systems.
Industrial Heat Pumps
Compressor lubricants for ammonia, CO₂ and hydrocarbon heat pumps operating under elevated temperature conditions.
HFC & HFO Refrigeration
Synthetic compressor lubricants for refrigeration systems using HFC and HFO refrigerants.