CO₂ Compression
CO₂ compressor lubricants are selected for compressors handling carbon dioxide as an industrial or process gas. Applications include industrial CO₂ supply, process recovery and liquefaction, food and beverage production, chemical feedstock and other manufacturing duties.
Where CO₂ directly contacts the lubricant, dissolved gas can reduce the operating viscosity of the oil–CO₂ mixture. Pressure, temperature, phase behavior, moisture, gas purity, compressor design and the location of each lubrication point therefore influence product and viscosity selection.
NEXT Lubricants supplies PAO formulations for lubricated CO₂ process compressors and oil systems. Enhanced oil recovery and the carbon-capture, transportation and storage chain have separate application pages because they introduce different gas compositions, pressures and operating requirements.
Key takeaways
- This page covers industrial and process CO₂ compression, including supply, recovery, liquefaction, food and beverage, chemical-feedstock and manufacturing applications.
- CO₂ dissolved in the lubricant can reduce operating viscosity where direct gas–oil contact occurs.
- CO₂ has a critical point of approximately 31.0°C and 73.8 bar. Both temperature and pressure determine whether the fluid is gaseous, liquid, dense-phase or supercritical.
- Moisture in a CO₂ stream increases corrosion risk and affects lubricant condition, materials and compressor reliability.
- Compressor design determines whether the lubricant contacts the process gas or remains isolated in bearings, crankcases, seals or auxiliary oil systems.
- NEXT PAO, NEXT GPL PAO and NEXT GPL PAO-FG cover different CO₂ process duties, purity requirements and ISO viscosity grades.
Compression process
How CO₂ compression works and the compressor's role
Industrial CO₂ originates from dedicated supply systems, fermentation, chemical production and other process streams. Depending on the application, the gas passes through separation, purification, drying, compression, cooling and liquefaction stages before storage, distribution or reuse.
The compressor raises the CO₂ pressure required for the next process stage. Facilities use reciprocating, rotary screw, centrifugal, diaphragm and other compressor designs according to flow, pressure ratio, purity and final delivery conditions.
Lubricant exposure differs substantially between compressor designs. Oil-injected screw compressors and lubricated reciprocating cylinders create direct gas–oil contact. Centrifugal, diaphragm and oil-free reciprocating designs often isolate the lubricant from the process gas while retaining lubricated bearings, crankcases, seals or auxiliary equipment.
Industrial CO₂ Supply
CO₂ compressors are used to increase gas pressure for industrial distribution, storage and reuse across manufacturing and process applications. Compressed CO₂ is used for applications including inerting and chemical processing.
CO₂ Recovery & Liquefaction
Industrial facilities can recover CO₂ from process streams and compress it for purification, liquefaction, storage or reuse. Lubricant selection depends on compressor design, pressure, temperature and the purity required downstream.
Food & Beverage CO₂
CO₂ is widely used for beverage carbonation, brewing and food-preservation applications where gas cleanliness is particularly important. Some systems therefore use oil-free compression, while lubricated systems may require a lubricant meeting the site's food-grade or incidental-contact requirements.
Chemical Feedstock & Urea Production
Compressed CO₂ is used as a feedstock in chemical processes including urea production. Atlas Copco specifically positions high-pressure CO₂ compressor technology for applications including urea production.
Industrial Process CO₂
CO₂ is also compressed within industrial processes where it acts as a working gas, reactant or reusable process stream.
Selection
Factors Affecting Lubricant Selection
CO₂ compressor lubricant selection depends on the compressor design, process-gas exposure and complete pressure–temperature envelope. Fresh-oil ISO viscosity alone does not define lubricant performance inside the operating compressor.
- Compressor Design and Gas–Oil Contact Determine which components require lubrication and whether the oil contacts the CO₂ directly or remains isolated in bearings, crankcases, seals or auxiliary systems.
- CO₂ Pressure, Temperature and Phase Determine whether the fluid is gaseous, liquid, dense-phase or supercritical and influence density, solubility, compressor loading and lubricant exposure.
- CO₂ Dilution and Operating Viscosity Determine the film thickness available after dissolved CO₂ and operating temperature reduce the lubricant’s effective viscosity.
- Moisture, Purity and Process Contaminants Influence corrosion risk, lubricant stability, material compatibility, deposit formation and the need for gas drying or additional separation.
- Product-Purity and Carryover Requirements Determine the required lubricant volatility, separation behavior and food-grade status where compressed CO₂ enters purity-sensitive processes.
Process
What NEXT needs to recommend a lubricant
A lubricant recommendation is based on the information below. Provide whatever information is available; NEXT will identify whether any additional details are required.
- Compressor Details Manufacturer, model, serial number and compressor type, such as reciprocating, rotary screw or centrifugal.
- Current Lubricant and Performance Current oil, oil volume, operating hours and any problems with viscosity, deposits, consumption, carryover or lubricant life.
- Gas Composition Main hydrocarbon components and any water, CO₂, H₂S, nitrogen, oxygen or other substances present. An existing gas-composition report can also be provided.
- Operating Conditions Suction and discharge pressures and temperatures, oil temperature and relevant operating limits for each compression stage.
- Application and Specific Requirements How the compressor is used and any purity, catalyst, material-compatibility, minimum-viscosity or other application-specific requirements.
- Final Recommendation NEXT evaluates the available information and confirms the recommended product, lubricant chemistry and ISO viscosity grade, with compatibility and changeover guidance where required.
Benefits
Operational Benefits of Correct Lubricant Selection
Selecting the lubricant according to the compressor, CO₂ conditions and purity requirements supports reliable process operation.
- Stable Operating Viscosity Helps maintain sufficient film strength after the effects of CO₂ dissolution and operating temperature are considered.
- Reduced Unplanned Downtime Helps prevent lubrication-related wear, overheating, deposits, valve problems and unexpected compressor shutdowns.
- Reliable Component Protection Supports the protection of bearings, cylinders, piston rings, packing, rotors and other oil-wetted components.
- Reduced Carryover and Purity Risk Low-volatility formulations help limit lubricant consumption and downstream contamination.
- Clean and Reliable Operation Oxidation stability and deposit control help maintain clean valves, cylinders and oil-system components while reducing unplanned downtime.
- Longer and More Predictable Service Life Improved resistance to oxidation, contamination and viscosity change supports controlled maintenance intervals.
products
Recommended NEXT CO₂ Compression Lubricants
NEXT PAO
Dry CO₂ / CO₂ Liquefaction & Process Compression
Base Oil: PAO
ISO Range: 15 – 320
NEXT GPL PAO
Industrial Process CO₂ / Chemical Feedstock Compression
Base Oil: PAO
ISO Range: 32 – 680
NEXT GPL PAO-FG
Food Grade / Purity-Sensitive CO₂ Compression
Base Oil: PAO
ISO Range: 32 – 680
Cross reference tool
Our technical team can help identify the right product.
TECHNICAL SUPPORT
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.
Frequently Asked question
What type of oil is used in CO₂ process compressors?
CO₂ process compressors can use synthetic PAO lubricants where the compressor design requires oil lubrication. The correct product depends on compressor type, whether CO₂ directly contacts the oil, pressure, temperature, purity requirements and OEM specifications. NEXT’s current process CO₂ range consists of NEXT PAO, GPL PAO and food-grade GPL PAO-FG.
Does CO₂ reduce compressor oil viscosity?
It can. Where compressed CO₂ comes into direct contact with the lubricant, dissolved CO₂ can reduce the viscosity of the oil-CO₂ mixture. The amount depends on lubricant chemistry, pressure and temperature, which is why operating viscosity should be considered rather than fresh-oil ISO grade alone.
What happens when CO₂ passes its critical point?
CO₂ has a critical point of approximately 31.0°C and 73.8 bar. It becomes supercritical only when both temperature and pressure exceed those values. High-pressure CO₂ below the critical temperature can instead exist as a dense liquid, so pressure alone does not define the phase.
Do I need a food-grade lubricant for food and beverage CO₂?
Not automatically. Some food and beverage CO₂ compressors are oil-free specifically to protect gas purity. Where a lubricated compressor is used and the plant or process requires incidental-food-contact compliance, NEXT GPL PAO-FG is the dedicated food-grade option.
How is CO₂ process compression different from CO₂ refrigeration?
The same CO₂ molecule is involved, but the application and compressor operating envelope are different. CO₂ refrigeration uses R744 within a refrigeration cycle and has its own lubricant and oil-return requirements. This page covers CO₂ being compressed as an industrial or process gas.
Is carbon-capture CO₂ covered on this page?
No. CO₂ compression specifically associated with the capture, conditioning, transport and geological-storage chain is covered on the dedicated Carbon Capture & CCUS page.
Is EOR covered on this page?
No. Enhanced Oil Recovery is now a separate application page. This page covers industrial and process CO₂ compression; EOR-specific injection conditions and lubricant selection belong on the dedicated Enhanced Oil Recovery page.
Related Applications
Explore Other Gas Compression Applications
Enhanced Oil Recovery
Lubricants for high-pressure gas and CO₂ compression used specifically for reservoir injection and enhanced oil recovery.
Carbon Capture & CCUS
Lubricants for captured CO₂ across conditioning, compression, transport and geological storage.
Industrial & Specialty Gas
Lubricants for industrial gases including nitrogen, helium, CO₂ and other manufactured or distributed gas streams.