You don't have to take a vane manufacturer's word for any of this.
The clearest evidence is something the screw industry publishes itself: the recommended air-end overhaul interval of every four to six years.
That interval isn't arbitrary. It's roughly the point at which lost efficiency and bearing wear make opening the machine worthwhile.
Sit with what that concedes. An overhaul restores clearances and replaces worn bearings — so if a machine needs that on a schedule to recover performance, the performance loss isn't a possibility to be managed.
It's an expectation, planned in from the day of sale. The maker is telling you, in its own service literature, that the machine drifts from its spec and needs periodic surgery to claw it back.
This framing matters more than any single replacement-hours figure, because it removes the argument. It isn't a claim about whether a particular machine is "good" or "bad." It's the manufacturer's own maintenance schedule describing a wear path.
And the overhaul itself is a real line in the total cost of ownership: parts, labour, downtime, repeated once or twice across a 15-year life.
Each one only restores the machine toward its original spec — never above it — and the efficiency lost on the way there was paid for in electricity you can't get back.
A technology that seals on a self-renewing film has no equivalent scheduled intervention, because there's no clearance to restore.
Read the full engineering case → https://www.linkedin.com/pulse/why-screw-compressor-efficiency-declines-over-time-rotary-contaldi-usqkf/