By Ron Marshall, Marshall Compressed Air Consulting
Like any industrial equipment, the air compressors, dryers and associated components on your compressed air system need occasional attention. It is very tempting to stay out of that dark, hot and dirty compressed air room, especially if the air compressor is running trouble-free, but maintain the system you must. Maintenance intervals can be stretched for a while, but it usually comes back to haunt you in the end, like the old Fram oil filter commercial says, “Pay me now or pay me later.”
If you have compressors that run continuously, you need to be especially diligent. It is often quite easy to relate the oil changes of your compressor lubricant to the oil changes for your own personal vehicle, thinking infrequent oil changes are acceptable, but for a compressor that runs all the time, it is important to ensure the lubricant stays in good condition, requiring timely changes to the compressor oil, often more frequent than you would expect.
Air compressor lubricant for oil-injected screw compressors is fairly expensive, but for a few good reasons. The duty inside a screw compressor is not normal. The lubricant reduces friction in the internal parts, like all lubricants, but it is also in direct contact with compressed air at high pressure, exposing it to the negative effects of oxygen. The oil is also used as a coolant, carrying away the heat of compression. It captures particles of dirt that are sucked into the compressor and get past the inlet filter, reducing its quality. And it traps the condensed moisture that forms when air is compressing, contaminating it further.
Compressor lubricants have additives to prevent oxidization and to extend its life in these harsh conditions, but these measures only last for so long. Once the lubricant reaches the end of its lifetime, if pushed beyond normal, damaging deposits will start to form inside the compressor that will clog up bearing and cooling surfaces with varnish. Its only a matter of time before overheating, bearing wear, and oil carryover cause major rebuild costs, or worse, the total failure of the compressor.
Some tips about compressor maintenance: