Vacuum Pump Vibration Tracker (ISO 10816)

Per ISO 10816, up to 1.12 mm/s RMS is new-machine condition (zone A) and up to 2.8 mm/s is acceptable for unrestricted long-term operation (zone B). Between 2.8 and 7.1 mm/s the machine should be scheduled for corrective maintenance (zone C), and above 7.1 mm/s vibration is severe enough to cause damage (zone D).

Check for carry-over first. A liquid slug or powder carry-over coats or chips the lobes, unbalancing them instantly; timing gears can also be bruised. Flush per the maker's procedure, re-measure, and only strip the pump if vibration stays high or the lobes show contact marks — running on regardless wrecks the timing gears.

On the pump bearing housing nearest the inlet, horizontal — as close to the bearing as possible, on stiff metal (never on covers or guards). Take horizontal, vertical and axial readings if you can; use the highest for the ISO grade and always re-measure at the same spot, load and speed.

The usual suspects are vane wear (rotary vane), lobe timing wear (roots), liquid slugs and process deposits on rotors, coupling misalignment and bearing wear. A frequency spectrum tells them apart: imbalance shows at 1× running speed, misalignment at 2×, bearing defects at non-synchronous frequencies, and looseness as a raised noise floor with harmonics.

Velocity in mm/s RMS, 10–1,000 Hz. ISO 10816 zone tables are defined on broadband RMS velocity because it weights low- and high-frequency faults evenly for general machines. Acceleration (g) suits high-frequency bearing analysis and displacement (µm) suits low-speed machines, but neither maps onto these zone boundaries.