How do you evaluate vibration? My view is from a simplified European perspective so I try to follow a ISO standard. My favorite is the venerable ISO 10816-1 that is based on a limited shaky foundation from the 1950´s. To make it further easy to use as it was in the beforetime I look at all machines as large machines on weak foundation so it makes my need to remember numbers so limited so I can handle it.
So if a machines vibration measured according to the ISO is less than 2.8mm/s it is ok for new machine delivery and will live a long and happy life, I would likely accept 3.0-3.2 mm/s also as decimals in this area have limited value in my view.
When the machine reach formally 7.1 mm/s you should analyze and repair and get it down to around 3 mm/s depending on the machines life, cost for fix, life expectancy and time available, you may need to settle for something slightly worse.
If your machine reach 18mm/s you should avoid operation, investigation and repair is mandatory. Diesels, reciprocating compressors and hammer mills may be excluded.
Company record is currently 200mm/s on rotating machinery then you should tip toe out of the danger zone. Remember this my simplified view to make it easy, there are 10+ standards differentiating all kind of machines and a full CD when all vibration related standards are included. In my view comparing to some time proven limits give at least some guideline when machines need to be evaluated.