Replacing oil with pure water removes contamination at the source. A water-lubricated oil-free screw compressor uses water to seal, cool and lubricate the compression chamber, delivering ISO Class 0 air while exploiting water strong cooling for efficient, near-isothermal compression. Choose it where air purity is non-negotiable and the lower discharge temperature is a real advantage.
How water lubrication works
In a water-lubricated screw machine, treated water is injected into the compression chamber to seal the rotor clearances, remove heat and lubricate the motion. Because no oil is present anywhere in the compression path, the air is oil-free by design rather than relying on downstream filtration.
The high heat capacity of water keeps compression close to isothermal, which reduces the work needed and keeps discharge temperatures low. The compression elements use corrosion-resistant materials, commonly stainless steel, for long life with water.
- Water seals, cools and lubricates the chamber
- No oil in the compression path, so Class 0 by design
- Near-isothermal compression lowers work
- Corrosion-resistant elements, commonly stainless steel
Water-lubricated versus dry oil-free compressors
Water-lubricated machines generally run cooler and avoid the higher temperatures and coatings associated with dry-running screws. They also avoid waste oil and oil-filter costs, with routine maintenance focused on water quality and air filtration.
They require attention to water treatment and the water circuit, since scale or impurities would affect sealing and the compression element. The best choice therefore depends on site water quality, duty and operating environment.
How to select and maintain a water-lubricated machine
Define the required pressure and flow, then match a model so normal demand sits within its range. Confirm the water-treatment arrangement that protects the element and keeps the injected water clean.
Plan redundancy for continuous processes, monitor discharge temperature and the water circuit, and schedule routine checks of air filters, the water filter and drains. Proper inlet conditions protect both purity and efficiency.
- Match pressure and flow to the real demand
- Specify water treatment to protect the element
- Provide redundancy for continuous duty
- Monitor the water circuit and discharge temperature
- Maintain air filters, water filter and drains
Real water-lubricated models: pressure, flow and power
FAD values correspond to the listed pressure options, from low to high pressure.
The table lists real water-lubricated models with pressure options, free air delivery and motor power. Select the model whose flow range comfortably covers normal demand at the chosen pressure.
Smaller machines from 7.5 to 55 kW serve lower flows, while larger water-cooled frames extend to hundreds of kilowatts for high-demand Class 0 processes.
Typical applications
Water-lubricated compressors are widely used in pharmaceutical, food and beverage, electronics and other processes where even trace oil is unacceptable. Their low running temperature and clean air make them a practical choice for continuous sensitive duties.
Modern controllers integrate with plant monitoring, report the status of the water circuit and faults, and can coordinate the compressor with other units.
What to confirm before you order
- Required air purity and whether Class 0 is essential
- Pressure and flow across the real duty
- Water-treatment arrangement for the circuit
- Redundancy for continuous processes
- Monitoring of the water circuit and discharge temperature
- Site inlet conditions and maintenance access
Frequently asked questions
Is a water-lubricated compressor truly oil-free?
What are the benefits of water lubrication?
What maintenance does a water-lubricated compressor need?
Does water cause corrosion inside the compressor?
When should I choose water-lubricated over a dry oil-free compressor?
Can water-lubricated compressors run continuously?
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Share your Class 0 air requirements, pressure and flow, and we will recommend a water-lubricated compressor package with the right water treatment and redundancy.
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