A rotary screw compressor floods its air end with oil to seal, cool and lubricate it. The separator takes that oil back out of the air before it leaves the machine.
These are not fuel/water separators, and the two are often confused when ordering. A fuel/water separator pulls water out of diesel; a compressor air/oil separator pulls lubricating oil back out of compressed air. If you came here looking for the diesel part, you want fuel/water separators instead.
Inside a screw compressor the oil and the air leave the air end as a mist. The separator element coalesces that mist back into droplets heavy enough to drain to the sump, and a healthy element holds carryover into the air line down to a few parts per million. When it starts to fail you see it twice over: oil appearing downstream where it should not be, and oil consumption climbing because the machine is losing its charge into the pipework.
Separators are changed on differential pressure as much as on hours. As the element loads, the pressure drop across it rises, and every extra bar of drop is energy the motor spends for nothing. Use the limit and the interval in your compressor’s own manual — they vary by machine, and the manual is the authority, not us. Why separators fail covers the failure modes, and buying a separator covers what to check before you order.
Both elements below seal on two inside diameters rather than a gasket, so the second inside diameter matters as much as the first when matching a replacement. Send us a photograph of the old element and the compressor plate and we will confirm it.
2 separator numbers we are asked for most often, across MANN-FILTER. Our range is far wider than this — if your number is not listed, it is very likely we can still supply it or match an equivalent.
MANN-FILTER
Compressed air / oil separator
MANN write this number as LB 13 145/3. Second inner diameter 111 mm.
Typical applications Rotary screw compressors and vacuum pumps.
MANN-FILTER
Compressed air / oil separator
Second inner diameter 71 mm.
Typical applications Rotary screw compressors on off-road and industrial plant.
This is a shortlist, not our range. Send us the number stamped on the old element, or the make and model of the machine, and we will identify the right part, confirm the fitment and quote it with availability. We can also cross a number from one brand to its equivalent in another.