Champion

The Myth:

Piston air compressors do not need regular servicing, and will run well for years without attention. By contrast, rotary screw air compressors are "service intensive", and can prove very costly from a service perspective.

Analysis:

This is a common myth, particularly among compressed air users who, in response to increasing compressed air demand, may have recently upgraded from a piston compressor to a rotary screw air compressor.

Service costs are, by their very nature, easy to measure and isolate. Compressor owners who migrate from piston to rotary-screw technology can sometimes perceive a face value increase in air compressor plant service costs. A more rigorous compressor "total-cost-of-ownership" analysis will reveal a number of less-obvious cost factors that, when factored in, show the economic truth of the matter.

One such factor is the cost of the energy (usually electricity) associated with running a compressor. Whether with screw or piston air compressors, energy savings can be realised by ensuring the compressor is regularly serviced. Both rotary-screw and piston compressors will continue to run without proper servicing - much the same as the family car. With the family car, if servicing is postponed, the car's fuel consumption will increase dramatically. Precisely the same "maintenance/fuel" relationship occurs with any form of air compressor. It is not uncommon for an air compressor to use 20 to 30 per cent more electricity due to clogged inlet air filters and separator elements.

Similarly, carbonisation on unserviced piston air compressor valves can result in an efficiency loss of up to 30 to 40 per cent. The end result is that an unserviced piston compressor may experience a drop in efficiency to as low as 50 per cent. At this level, the poorly serviced piston compressor would be taking twice as long to compress the air, and the power consumption may well have doubled. Superficially, the piston air compressor will appear to be running smoothly and ironically due to the poor efficiency will not suffer any heat build-up.

It is important to note that air compressor service costs are typically of the order of one tenth of energy costs. As a result, skimping on air compressor servicing is a classic case of "saving cents, but wasting dollars".

Conclusion:

While it is true that piston compressors can run for a very long time without servicing, so too can rotary screw air compressors. It is also true that, in the absence of regular servicing, the efficiency of any air compressor will fall, causing the power costs to quickly increase to a level that usually exceeds the "savings" made on the compressor servicing. The greatest "total-cost-of-ownership" saving comes from regular scheduled servicing of the air compressor.