The following is an interview with Usama Iqbal, a sales engineer for oil-injected compressors at Atlas Copco Pakistan’s Oil-Free Air Division. We discussed some myths about oil-lubricated compressors in the industry to find out how factual they are
1. Is it true that the compressed air of a VSD oil-lubricated air compressor contains more amount of oil vapors as compared to other compressors?
We do get to hear that at lower speed a VSD compressor has more oil carryover. In fact at reduced airflow, the oil separation process works even well due to lower air velocity. Lower pressure and high temperatures are the two factors that result in higher oil carryover.
2. The filtration system used in oil-less air compressors results in more energy consumption. Is it true?
Every line filter comes with an additional pressure drop that results in additional energy consumption, but the efficiency of the compressor element should also be taken into account. An oil-lubricated screw element is, for example, more energy-efficient compared to an oil-free screw element, because of the oil-injection. To reduce the risk of oil carryover, you need a filtration system that depends on the required air quality of the process/product.
3. Many believe that the compressed air of an oil-lubricated air compressor is low in quality because of oil contamination. What are your thoughts on this?
The required air quality is different for each process and application. A good filtration system helps in reaching a high quality of air (as defined in the ISO 8573). Industries like food and beverage, semiconductor, textile weaving, and medical will always opt for oil-free air because of the risk that the end product could be contaminated. However, many applications are perfectly suitable to operate with compressed air from an oil-type screw compressor.
4. Is there any chance of oil dripping out from an industrial air compressor?
If there is a leak then there is a chance of oil dripping out of the compressor. Most of our compressors have an oil-containing frame to avoid oil spillage to the environment in case of any oil leaks from the machine.
5. Can we use an oil-lubricated air compressor in the food and beverage industry or the healthcare industry keeping in mind the quality of compressed air?
Atlas Copco recommends the use of oil-free compressors for those applications whose final product is to be consumed directly and as per standards of FDA (Food & Drug Authority) and BCAS (British Compressed Air Society), compressed air must be oil-free, luckily, we have both technologies in our product portfolio. Although we recommend oil-free in those segments, we see many customers asking for oil-lubricated machines (with a filtration system, which we are also able to provide). It’s always up to the customer to decide which compressor technology is the best for their application.
6. Is it possible that the filtration system used in an oil-lubricated compressor can cause unnecessary fluctuations in its working pressure?
No, the filters are passive and have a fixed pressure drop. This might slightly vary during the lifetime of the filter, but this is always considered while designing a compressed air network. Besides, the filters are equipped with pressure drop monitoring sensors, so any irregularity in the compressed air network is reported to the user.