Reduced ultimate vacuum, rising noise, oil misting and elevated running temperature, and the failure sequence behind them.
Vane wear presents in a consistent order: reduced ultimate vacuum, then increased noise, then oil misting from the exhaust, then elevated running temperature.
Falling ultimate vacuum is the earliest indication and the cheapest to monitor. Once the housing bore is scored, replacing the vanes no longer restores the pump.
Source: manufacturer failure guidance, oil-lubricated rotary vane series.
The manufacturer documents a distinct failure mode for non-genuine replacement vanes. They may become brittle or delaminate, absorb oil and swell, and having swollen, stick in the rotor slots.
Source: manufacturer guidance on non-genuine replacement vanes.
A vane that has swollen and jammed in its slot cannot extend, and therefore cannot seal. The pump is at stage 2 of the sequence above from the point at which the part was fitted. A vane that delaminates also sheds material into the pump.
A 20,000-hour vane life is published for the dry-running VT/VX X-series. The figure applies to a dry pump with carbon vanes.
It does not apply to the oil-lubricated U-series. No vane life is published for the oil-lubricated series.
The figure is frequently quoted for oil-lubricated pumps in error. A maintenance plan built on it rests on a figure the manufacturer never issued for that machine.
The question has been put to the manufacturer. If a figure for the oil-lubricated series exists it will be published here. If the answer is that no such figure exists, that answer will also be published.
The vane set is specific to the pump variant and is identified from the nameplate.
Four vanes in an eccentric rotor. Watch the tips stop reaching the wall — and watch what the gauges do about it.
| Figure | Value | Source |
|---|---|---|
| Vane life, oil-lubricated series | NOT PUBLISHED | No manufacturer figure located. Enquiry submitted. |
| Vane life, dry VT/VX X-series | 20,000 hrs, a different pump | Manufacturer VT/VX documentation. Does not apply to oil-lubricated pumps. |
| Non-genuine vane failure mode | Brittle / delaminate; absorb oil and swell; stick in rotor slots | Manufacturer guidance on non-genuine vanes |
| Wear pattern from uneven contact | Washboarding, leading to housing damage | Manufacturer failure guidance |
| Vane wear limit | NOT PUBLISHED as a dimension; the set is replaced against trended wear rate | No manufacturer figure located. |
No vane life is published for the oil-lubricated U-series. The question has been put to the manufacturer, and no figure appears in any document we have located.
The 20,000-hour figure in general circulation belongs to the dry-running VT/VX series and does not apply to oil-lubricated pumps.
The symptoms appear in order: reduced ultimate vacuum first, then increased noise, then oil misting from the exhaust, then elevated running temperature. Falling ultimate vacuum is the earliest and cheapest to monitor.
No figure is published for the oil-lubricated series. The 20,000-hour figure in circulation belongs to the dry-running VT/VX X-series. Vane length should be recorded at each service and the wear rate trended.
The most common mechanical cause is vane wear: the tips no longer reach the housing wall, a clearance opens, and gas leaks back. A saturated oil separation element, a blocked intake filter and degraded oil should also be checked.
The manufacturer documents that non-genuine vanes may become brittle or delaminate, absorb oil and swell, and stick in the rotor slots. A vane that cannot extend cannot seal, and the resulting uneven contact scores the housing bore.
Parts: Vacuum pumps · Lubricants & oils
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