by
HbJ » Mon Sep 03, 2012 10:45 pm
Basically all properly maintained pumps. We're running Balzers DUO 004B, E2M5 and E2M30.
Generally it's _always_ a good idea to use an exhaust silencer/oil mist filter etc. as all vacuum pumps tend to show considerable exhaust noise.
Use only highest-quality oils (P3, Inland 45, maybe N62+). Other, inferior oils tend to sludge the pump, blocking oil channels and causing damage to mechanical components as well as noise.
Check O-rings and gaskets. Any gurgling noise usually is a sign for a leak. Find and fix it.
Place the pumps on a rubber mat like the ones used for washing machines or dryers. Many noises one attributes to the pump are actually vibrancy.
Don't use too large pumps. All conventional rotary-vane pumps are more noisy on final vacuum. Please note that oil-backstreaming increases when the pump reaches its final vacuum.
Furthermore each of them has their own sources of noises:
- Balzers: When these pump reach their end-vacuum, they tend to be show "Ölschlag" (I didn't find a proper English translation) which basically means the valves tend to make noises as there's nothing to pump. After removing the gas ballast cover you find a screw which you can use to adjust the intensity of the valve noises by allowing some air into the pump. Besides that, those pumps are marvels of perfect German engineering. They're extremely quiet and reliable.
- Edwards: The motors for the smaller pumps produce grinding noises when they age as their English (=junk) bearings fail. Those can be replaced with quality spares to reduce noise emission. Another issue are the vane springs which tend to stick, i.e. not squarely pushing the vanes to the pump housing. Replace those in preventive maintenance once a year. Also check for leaks causing gurgling, especially on the gas ballast.
