demax - 25-8-2005 at 03:13
I have typed in many different combinations but cant find anything to give me some pointers on constructing an exhaust filter for an oil vacuum pump I
have just been offered (although not my first choice of setup). I was thinking of running a hose from the pump to a chilled bucket of water but feel
this will stress the pump. Any body have any ideas or directions?
-demax
[Edited on 25-8-2005 by demax]
BromicAcid - 25-8-2005 at 19:14
I get the same problem with my air conditioner pumps, that the oil starts to spray out when they run, as a consequence I run my exit pipe into about 4
or 5 inches of dry sand, it stops all spray in my experience and shouldn't stress the motor, just don't let the sand get into the pump.
bio2 - 25-8-2005 at 21:41
Sand huh? Good idea will have to try it.
A jar filled with loosely packed tissue paper with the exhaust tube at the bottom works well. Keep the tube short and as large or larger than the
pumps outlet.
To recover the oil you can use an upside down SS fuel filter (metal screen type) plumbed backwards. Walla automatic oil separator/recovery unit.
demax - 29-8-2005 at 02:38
Hi,
appreciate the replies coz where i live they want more than 200USD for such a filter.
Um;
Can the lid be left on the jar and say bore a hole in the lid to then run the tubing into the jar?
Jar size is relevant?
'Tubing must be bigger than the outlet on the pump', does this mean rigging up some special plumbing and why is this necessary? Same
principle as a car exhaust?
Recycling no good coz oil will be full of solvent residue I am tipping
take it to,
Demax
tnhrbtnhb - 25-4-2007 at 01:37
Hello, everyone.
I want to dredge this thread up, because none of the things mentioned here really work to filter mist per se, and I need something that will :-( . I
would like to point out that I duly searched the archives like everybody says you should :/....
So, any ideas on where to buy (in Ottawa, Canada) OR how to build an oil mist filter to filter oil mist from the exhaust of a rotary vane pump?
I tried the ideas listed here, and I can still smell the oil mist coming out. Which makes sense after all, given that it's something like 0.3
microns or something, it's not going to be filtered by sand or tissue paper. They may prevent the mist from dispersing in to surroundings if there
is a very low volume of gas coming out of the vacuum pump, but that won't help when pumping down relatively large vessels.
If it is not economical or practical to build a filter, I suppose exausting it to the outdoors is okay?
Maya - 25-4-2007 at 02:39
a BIG car fuel filter which is put in reverse in the exhaust line
not_important - 25-4-2007 at 04:21
Maya has a good suggestion, but rather than a fuel filter consider using an air filter. You want a lot of surface area so that the gas flow is slow. A
visit to a automobile scrap yard might find you the filter enclosure, then there's some work in adapting it to the pump's vent. Otherwise a pair of
metal plates with matching holes for bolts, sandwiching the air filter between them, and with a large center hole in one plate holding a fitting to
connect to the pump's exhaust.
An automotive oil filter would seem to work, except that the pressure drop is an order of magnitude too high, the vac pump would be less than happy.
The other thing that might help is to restrict the volume of gas flow during the early stages of pump down. It's the rapid flow of gas that makes a
lot of mist, if you can stand a slower pump-down it could reduce the amount of mist formed in the first place.
leu - 25-4-2007 at 18:51
An inexpensive method that works is to attach a vertical copper tube about a meter long to the exhaust tube and solder in enough copper mesh scrubbing
pad to collect the oil and return it back where it belongs 
tnhrbtnhb - 25-4-2007 at 20:45
But would any of these methods actually reduce the amount of oil mist to not stink a place up? And even minute quantities are not healthy.
I don't think any of these methods would really filter out a great fraction of the mist, though, except maybe - I don't know, though - the air filter.
Would they?
I mean, sure they'll reduce the output, but by no means eliminate it. If I have to exaust to the outdoors anyway, there's hardly any point in
spending all that money on a filter....
bio2 - 25-4-2007 at 22:15
A " real" coalescent separator for oil mist does not
filter out the mist per say. Rather the velocity is dropped
and the exhaust gas is forced to change direction a
few times through fine mesh screens.
The methods suggested all work to a point but nothing
gets all the smell out .
A large truck fuel filter performs nearly as well as a high priced
coalescent separator. If you don't want to return the oill
to the pump due to entrained solvent then allow the
gravity return to collect in a rag or another vessel.