One oil aerosol cloud inside a pharmaceutical air line can trigger a batch recall; the same residue on a PCB assembly can kill a high-value production run. ISO 8573-1 Class 0 is the compressed-air purity grade that pharma and electronics buyers use to remove that risk at the source. Here is what the class actually requires, what it does not cover, and how to specify a compressor and treatment package that stay audit-ready.
What ISO 8573-1 Class 0 Actually Means
ISO 8573-1 grades compressed-air quality across three contaminant groups: solid particles, water, and oil. Buyers often fixate on the oil column, but a compliant specification must cover all three.
- Particles: Class 1 allows up to 20,000 particles of 0.1–0.5 µm per cubic metre, with tighter limits for larger particles.
- Water: Class 1 specifies a pressure dew point of −70 °C or lower; Class 2 is −40 °C and Class 3 is −20 °C.
- Oil: Class 1 permits no more than 0.01 mg/m³ of total oil. Class 0 is defined as a level agreed between supplier and buyer that is more stringent than Class 1.
In practice, buyers treat Class 0 as oil-free and expect proof from certified oil-free equipment or validated treatment. The distinction matters: Class 0 is a negotiated performance target, so you must still fix the measured limit and the test method.
Why Pharma Buyers Cannot Skip It
Compressed air in pharma often touches product, contact surfaces, or primary packaging. GMP audits expect controlled, dry, particle-free air. Uncontrolled oil vapour can contaminate the product, degrade active ingredients through oxidation, and create microbial risk when moisture condenses in piping.
That is why the full treatment train matters: an oil-free compressor plus a dryer and high-efficiency filters. Panrui’s PR-W water-cooled, two-stage permanent-magnet machines are built for 24/7 pharma and food duty and reach full-range Grade 1 energy efficiency under GB19153-2019. The treatment package uses 304 stainless steel piping and three-stage precision filtration to keep the air path clean. Learn more about the rotary screw air compressor range before you size the station.
Why Electronics Buyers Treat Class 0 as a Yield Issue
Optoelectronics and PCB plants are just as sensitive. Oil aerosol can prevent coating adhesion and leave conductive contamination; moisture and fine particles cause corrosion, lens hazing, and bonding defects. Class 0 oil plus a low dew point is the practical combination that protects yield.
How to Specify and Verify the Right System
Panrui’s range includes oil-free screw air compressors for fermentation and clean applications, alongside two-stage permanent-magnet variable-speed rotary screw compressors that cut energy use by 20–50% compared with conventional fixed-speed units.
- State the full class as ISO 8573-1 [Particles:Water:Oil], not just “Class 0.”
- Fix dew point and particle limits for the most sensitive process in the plant.
- Require a dryer and filtration train matched to the compressor, not a compressor-only quote.
- Ask for ISO 8573-1 test reports, maintenance logs, and oil-carryover evidence.
Frequently Asked Questions
Is Class 0 the same as oil-free?
Not exactly. Class 0 means a limit more stringent than Class 1 and is usually achieved with oil-free compressor technology, but you must still agree on the actual measured limit and verify it with a test report.
Do I need Class 0 on every air line?
No. Reserve Class 0 for product-contact and sensitive process air. Utility air such as cylinder actuation can run at a lower class and keep the system cost-efficient.
How do I verify a Class 0 claim?
Request ISO 8573-1 test data, a defined sample point, and maintenance records. Confirm the dryer and filters are sized for your dew point, not only for the compressor’s flow.
Match the machine to your purity target before you buy. Share your flow, pressure, dew point, and ISO 8573-1 class with Panrui, and we will specify a compressor and treatment package that stays compliant under audit. Contact us for a sizing recommendation.
