Will just changing the air/oil separator on a regular maintenance basis in a rotary screw compressors increase a compressor's efficiency thus reducing the compressor's engery draw?

Hi Larry,
We had a problem with an IR Rotary screw with exceptionally high oil consumption. And during the course of the investigation energy draw was recorded. Anyway the resolution was to change out the air/oil separator. (only 4 months old) After change out we could determine no difference in energy consumption.
Theoretically yes the appropriate maintenance should show some dividends but in this case we couldn't quantify any energy savings between a partially plugged oil separator and a new clean one.
regards.....

Larry,
Air/oil separators in rotary screw compressors add pressure drop to the system requiring the compressor to work harder and consume more power. New, clean separators will have only 1-2 psi of initial drop which gradually increases to 8-10 psi as the separator becomes fouled in service (most manufacturers recommend changing at 10 psi). This increased pressure drop definitely carries with it a power penalty. A common "rule of thumb" recognized by the US DOE for any compressed air system pressure drop is 0.5% power penalty for every 1 psi increase in pressure drop. Example: A 200Hp rotary screw compressor that operates 8,000 hrs./yr. with an 8 psi separator delta P will consume an extra $2,095 per year (at $0.05/kwh) over a new (2 psi) separator. This extra energy consumption is small in terms of percentages (and difficult to measure) but does exist and can amount to a lot of money in larger compressed air systems. Standard OEM oil filters are not designed to filter out the ultra-fine solids that are more prone to foul separators. Adding a high efficiency, low micron (1-3)rated bypass filter will remove the smaller solids that shorten the life of separators (and other compressor components).