Matthew Karam wrote:
over the weekend I had a vacuum system fail on me.
In a nutshell, from high to low vac:

vac chamber turbo pump electronic safety valve foreline trap
rotary pump oil mist filter exhaust hose


There were no power surges.

It looks to me like the safety valve overheated and failed.
This introduces a small air leak so the system can slowly vent.

The rotary pump spewed out all it's oil through the exhaust. The
filter was full, dripping and there's a puddle on the floor. The RVP
is almost completely empty.
I can't fathom what sort of failure could cause this.

I checked the exhaust filter for little bits of material (to see if
something crumbled inside the pump) but it was clean except for the
oil.

Is there a problem is these pumps are not perfectly level? I can't see
how that would cause this... but that's all I've got right now... it's
not that far off level...

Any ideas? Thanks everybody!


I've run Ultra High Vacuum systems for 40 years with no serious problems
!, Electron Microscopes !

My son was supervising the operation of a Mass-Spectrometer with a
Turbo-Molecular pump, RVP system when a Carbon-Fiber Vacuum coupling
failed on the high Vacuum side.
I don't know what it cost the manufacturers for repairs , but I know
the TMV pump tried to go into Full-afterburner mode and filled the
Ultra-high Vacuum system with pulverized metal dust when the TMV-pump
swallowed atmospheric air ! Which is why the inclusion of the
"electronic safety valve" This probably saved your TMVP!

I would suspect the diaphram in the "electronic safety valve" ruptured
on the roughing pump side and protected the TMVP and shut it down safely

It is ironic but a 2 stage rotary vacuum pump is not really designed to
handle large volumes of air. 99% of its operating cycle is pumping at ~
10u pressure. The exhaust port is part of a reed valve set-up sealed by
the flat spring-like reed which is made gas-tight by the oilbath
reservoir. Normal operation has only a trickle of bubbles flowing out
from under the spring, usually from bypass operation to flush moisture
(condense-able vapors ) from the pump. It is only during the initial
roughing cycle that a significant amount of air flows though the pump
and carries a small amount of atomized Vacuum pump oil with it, hence
the oil mist filter. The RVP is designed to pump down a Closed system.
not an open to the atmosphere system, so it is no surprise that it
flushed out its charge of oil when it was opened to the atmosphere.

BTW Philips/Ewards High Vac. now recommend using "AMSOIL" Compressor
oil ISO-46 (PCI) SAE 20 for their Vacuum Pumps. Much better pump life !

Yukio YANO