When food, pharmaceutical and electronics plants need an oil-free compressor, what Class 0 certification means, how heat affects oil-injected filtration, which oil-free technology fits, and how to test the air.
Choose an oil-free compressor when compressed air touches your product, its packaging or a sterile process, and when a filter failure would mean a recall. It removes the compressor as the source of oil, but not the need for dryers, filters and testing. Set the ISO 8573-1 air class from your food safety or quality system first, then compare oil-free compressor suppliers in the UAE against oil-injected packages with filtration.
This guide is for quality managers, plant engineers and buyers in food and beverage, pharmaceutical, medical device and electronics plants. It goes deeper on oil-free air than our guide to industrial air compressors in the UAE and Saudi Arabia, which sets out the ISO 8573-1 class table, compressor types, sizing and brands. Here we cover where oil comes from, oil-free versus oil-injected with filters, what a Class 0 certificate proves, the oil-free technologies, microbes, GMP expectations and how to test the air. Plants in the Kingdom can compare oil-free compressor suppliers in Saudi Arabia.
There are three sources, and an oil-free compressor deals with only the largest one.
Both routes can deliver clean air. The difference is how the risk is managed. Atlas Copco states that a correctly maintained oil-injected system with coalescing filters, which can remove oil down to 0.001 mg/m3, and activated carbon filters for vapour, can reach ISO 8573-1 Class 1, and it recommends oil-injected machines for general manufacturing where cost control matters. It recommends oil-free machines for food and beverage, pharmaceutical, medical and electronics plants, where contamination affects product quality or safety.
| Factor | Oil-free compressor | Oil-injected compressor with filtration |
|---|---|---|
| Oil in the compression chamber | None | Yes; removed by separator and filters |
| Risk of oil contamination | Compressor is not an oil source | Possible if a filter fails or is not maintained |
| Effect of high room temperature | Air quality not dependent on oil filter performance | Carryover and carbon filter life worsen with heat (see below) |
| Downstream treatment | Dryer and particle filters still needed; smaller oil treatment | Coalescing and carbon stages needed, with their pressure drop |
| Purchase price | Higher | Lower |
| Maintenance | Fewer oil-related parts | Regular oil, separator and filter changes |
Source for the table: Atlas Copco's comparison of oil-free and lubricated compressors. Atlas Copco sells both types, but its oil-free guidance naturally argues for oil-free air, so weigh it alongside your own risk assessment.
The filtration route is most fragile where compressor rooms are hot. Atlas Copco's Class 0 FAQ states that oil carryover through filter media rises exponentially with temperature: in its example, a compressor room at 30 °C can mean a compressor outlet at 40 °C and carryover of up to 20 times the filter's specified value. It adds that a rise from 20 °C to 40 °C can cut activated carbon filter life by up to 90%, that a saturated carbon filter gives no warning, and that higher temperatures also raise the oil vapour content of the air. Gulf compressor rooms regularly run hotter than that example. If you choose oil-injected air for a product-contact duty, design the filter stages for your real air temperature, shorten carbon change intervals accordingly and monitor oil content continuously.
ISO 8573-1 Class 0 has no fixed limit: as the main guide explains, the user and supplier agree a limit stricter than Class 1 and write it into the specification. Two practical consequences follow.
So a supplier's "Class 0" claim is only as good as the certificate behind it. Ask for the test report naming the model, the ISO 8573-1 edition, the parts tested, the sampling method, the test conditions and the agreed limits. Note also that a Class 0 compressor certificate covers the compressor outlet, not the air at your filler or tablet press.
Take the class from your own quality system, not from a brochure. Sources point in the same direction but differ in detail:
An oil-free compressor does not make air sterile. Atlas Copco's guidance on microorganisms in compressed air explains that the heat inside oil-free compression elements significantly reduces microorganisms but does not last long enough to count as sterilisation. The main lever is moisture: it states that most microorganisms need relative humidity of 75% or more, some grow between 50 and 75%, and below 50% there is normally no proliferation, and it treats a dew point that keeps relative humidity in the air below 10 to 20% as food and hygiene safe. That points to a dryer specified for a low dew point plus sterile filtration at the point of use where the process needs it. Our guide to compressed air dryers covers dew point and dryer choice in Gulf heat, including heat of compression dryers that suit oil-free compressors. Find dryers under air dryers in the UAE.
| Technology | How it stays oil-free | Typical fit | Example ranges stated by makers |
|---|---|---|---|
| Dry screw or tooth | No oil in the compression chamber; tooth machines use synchronising gears and several stages with intercooling for higher pressure | Medium to large plant air | Atlas Copco ZR/ZT screw and tooth; ELGi two-stage oil-free screw 45 to 450 kW |
| Water-injected screw | Water, not oil, is injected to cool the compression | Small to medium plants wanting single-stage oil-free air | Atlas Copco AQ: 15 to 55 kW, 3.3 to 9.1 m3/min, 7.25 to 12.75 bar; ALUP WisAIR |
| Scroll | Orbiting spiral compresses air with no oil in the chamber | Laboratories, medical, small food and packaging demands; quiet | Atlas Copco SF: 1.9 to 7.6 l/s, 10 bar, down to 53 dB(A); ALUP SpiralAIR |
| Oil-free piston | No oil in the cylinder | Small and intermittent demands | ALUP CleanAIR (stated as Class 0); ELGi oil-free piston |
| Centrifugal | Designed for large oil-free flows | Large, steady oil-free demand | See the main guide |
Atlas Copco notes the limits of scroll machines: they cost more per unit of air and do not suit high-capacity duty, where screw machines are more efficient. For tooth compressors it explains that the pressure ratio per stage is limited by discharge temperature, so higher pressures need several stages with cooling between them. For sizing the machine itself, see our guide on how to size an air compressor.
A specification is only real once the air at the point of use has been measured against it. Atlas Copco's overview of compressed air quality testing lists the main methods:
A validation plan should name the sampling points (at least after treatment and at each critical point of use), the parameters and methods for each, the acceptance limits from your specification, the testing frequency, and what happens when a result fails. Microbial sampling belongs in the plan wherever air contacts product. Run the first full set at the hottest time of year, when dryers and filters are working hardest.
Atlas Copco makes oil-free screw and tooth (ZR/ZT), water-injected screw (AQ), scroll (SF), piston and centrifugal compressors, publishes its Class 0 test approach, and cites Al Ain Farms in the UAE as a user of its oil-free VSD compressors.
ELGi offers oil-free screw and oil-free piston compressors, including a two-stage water-cooled oil-free screw range from 45 to 450 kW, states that its oil-free compressors are ISO 8573-1 Class 0 certified, and has its regional company in Sharjah.
ALUP lists the CleanAIR oil-free piston compressor, stated as delivering Class 0 air, the SpiralAIR scroll compressor and the WisAIR water-injected screw compressor.
Fusheng lists oil-free air compressors, including its GW series, in a range it has built since 1953.
When your specification is ready, post your oil-free air requirement and suppliers in the UAE and Saudi Arabia can respond. Treatment equipment is listed under compressed air treatment and compressed air filters.
More in this series: Screw vs Piston Air Compressors, Portable Diesel Air Compressors and Compressor Rental in the UAE and Saudi Arabia.
Not necessarily, but they must deliver air of a defined quality. Atlas Copco says food applications typically need ISO 8573-1 Class 0 or Class 1 and recommends Class 0 oil-free air for direct contact such as pneumatic conveying. An oil-injected compressor with well-maintained filtration can reach Class 1. The class should come from your HACCP study under your food safety system.
Yes, according to Atlas Copco, if the coalescing and activated carbon filter stages are correctly maintained. The risk is in the word maintained: filter failure or late changes let oil through, and Atlas Copco states that carryover rises sharply with temperature and that a saturated carbon filter gives no warning. In hot Gulf compressor rooms, design and monitor for that.
No. Atlas Copco states that the heat in oil-free compression elements significantly reduces microorganisms but does not last long enough to sterilise. Keep the air dry, since most microorganisms need relative humidity above about 50 to 75% to grow, and use sterilising grade filters at the point of use where the process requires sterile air.
EU GMP Annex 1 (2022) requires gases contacting the product or primary container to be of appropriate chemical, particulate and microbial quality, with oil and water content specified and pharmacopoeia monographs met where applicable. Gases used in aseptic processes must pass a sterilising grade filter of 0.22 µm maximum nominal pore size at the point of use, with periodic microbial monitoring.
Yes. Water rather than oil is injected for cooling, so there is no oil in the compression chamber. Atlas Copco's AQ water-injected range, 15 to 55 kW at 7.25 to 12.75 bar, is certified to ISO 8573-1 Class 0 (2010) according to the maker, and ALUP sells a water-injected screw under the WisAIR name.
No single frequency applies to every plant. Set it in your validation plan from the risk to the product: continuous dew point and oil monitoring where the risk is high, plus periodic laboratory testing of particles, oil and microbes at critical points of use. EU GMP Annex 1 requires periodic microbial monitoring of process gases in sterile manufacturing.
Featured image: Photo: Alf van Beem, CC0, via Wikimedia Commons
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