The industrial world has relied on compressed air for over 100 years. Multiple types of air compressors have been used, including piston compressors and rotary screw compressors. What is common between these, is that they use oil to lubricate the moving parts, to help sealing the air compressor. Oil is a good lubricant to keep metals from contact with each other. In some air compressor types like the oil-flooded screw compressors, the oil also functions as a heat transfer medium. However, it is evident that oil-contamination is an important risk to consider and must be avoided.
Most people never come to think twice about these various roles the oil in air compressor plays. This very same compressor lubricating oil can end up in the product it helps to produce through compressed air that touches it – and in the air we all inhale with the breaths we take…and there is a lot of it!
Small streams make big oil-flooded rivers
The most common industrial air compressor is the oil-flooded screw compressor. Estimates put the installed population of oil lubricated screw compressors in Europe alone at about 1 Million units. Oil-flooded screw compressors come in various sizes from 2kW (or 3hp) to 400kW (or 600hp) and higher. These compressors have usually anywhere between 4 liters (one Gal) and 100 liters (25 Gal) of oil. This oil is changed, pending on the oil type, every 2,000 (mineral oil) to 8,000 hours (synthetic oil). With varying duty cycles, 60 – 65 million liters (15 – 16 million Gals) of oil is used in these compressors annually.
When oil-flooded screw compressors are operated, air and oil mix, and oil is removed from the air in a separation system. Well, most of it anyway. Modern screw compressors use various mechanical ways to separate oil, resulting into nominal oil carry over between 2 and 4 ppm in compressed air. This may not sound like much but it comes to 2 to 4 kg of residual oil in one million kg of air. From these basics and typical duty cycle profiles for various compressor sizes, we can deduce that oil lubricated screw compressors alone produce between 8.2 and 10 million kg (18 and 22 million lbs) of oil in the air every year. This is the amount for Europe only. Add to this other oil lubricated compressor types and other continents and the number gets staggering. It is the small streams that make big rivers.
Please note that the above-mentioned numbers do not include the oil in the gas state of matter. The heat in compression vaporizes oil into gas form and most of it is not captured in oil separation. Oil is released in both gas and particle phase. When compressed air cools down, oil vapors condense in the air lines to oil droplets in particle form.
Oh, and there is more – the amount of oil released from the air compressor and filters increases when the compressors get older. This means that the nominal 2 to 4 ppm oil carry over rate can increase to 8 to 10ppm before the filter change. And, that’s a lot of cumulative additional oil in the air from each and every air compressor.
Oil in compressed air is a problem and therefore it should be removed. A majority of oil in compressed air will be captured in the compressors’ moisture separators and in various types of compressed air filters. Still, a large quantity of oil is left in the air – air that touches many products it helps to produce, the food we eat or the air we breathe. That is not good and it is not desirable.
There is a 100% oil-free way out of this
Tamturbo’s 100% oil free technology provides a perfect and an unmatched solution to the problem. Not a single drop of oil is needed to compress the air!
Our variable high-speed centrifugal compressor is compact, silent and has a very long lifetime as there are no wearing parts.
The High-Speed Turbo compressors use active magnetic bearings (AMB) that keep the motor shaft magnetically levitating at all times. This means there are no gears or bearings to lubricate, no mechanical seals or any other parts that touch or wear and thus, no oil and therefore no oil filters etc.
Without oil in the system, our compressors are completely risk-free from oil adding ANY contamination in compressed air.
100% oil free Tamturbo High-Speed centrifugal compressor produces ISO 8573-1, Class 0 oil free air without the complication of needing downstream equipment selection for oil removal and costly oil services and waste disposal.