RE: [ihc] oil bath filters

["Steven Stegmann" <steve.stegmann@xxxxxxxxxxxxx>]

Well, nobody expects the dust to "fall out of the air", that's not how it
works.  The airflow through the oil blasts the oil into a mist inside the
air cleaner.  If there is enough small oil droplets they will contact a
sufficient portion of the airflow and enough dust will be removed to protect
the engine.  The dust will stick to any oil it touches, the trick is to have
enough droplet so that all the dust has a chance to hit the oil.

Thought experiment:
If there are just two large droplets, it is clear that all of the air won't
touch the oil, most of the air will just go around.  As you increase the
number of droplets, you increase the surface area of the oil and give the
air a better chance to touch some oil.  If you can make a nice wet oil mist,
it will work very efficiently.  This is exactly what a wet scrubber is for a
power plant and they are *very* effective.  They are also large and power
consuming (pumps & nozzles to make the mist).  An oil bath air cleaner on an
engine does not make anywhere near as effective a mist.  Therefore it is not
as effective.

I've seen them on cars (like my Dad's 50 Ford).  I don't know why they were
used there (maybe paper filters of the time were really bad or failed in
really wet weather, does anyone know?), but they were on tractors because a
paper filter of the time would be hopelessly clogged by the heavy dust.  In
the case of tractors, those engines accumilated a lot of hours and the
filters were good enough.  With normal maintenance those engines survived
just fine.

Steve

-----Original Message-----
From: owner-ihc@domain.elided [mailto:owner-ihc@domain.elided]On Behalf Of
James Lidberg
Sent: Wednesday, February 18, 2004 8:47 PM
To: John Hofstetter; IHC Digest
Subject: [ihc] oil bath filters


I remember the oil bath filter on my dad's 53 Ford, the air had to bubble up
through the oil and then got sucked up
into the wire mesh, it was like a copper pad used to clean pots with, except
steel. The oil would collect on the mesh
and eventually drain back down. The dirt too. If there was dirt in the air
would it not get trapped in the oil as the
air bubbled though it and also in the oil coated mesh?

- Jim in Mesa


Date sent:      	Tue, 17 Feb 2004 09:28:57 -0800
Subject:        	Re: [ihc] Postal 800 Purchased + help with some questions
From:           	John Hofstetter <hofs@domain.elided>
To:             	James Lidberg <jameslidberg@domain.elided>,
	David Bongo <dbongo@domain.elided>,
	IHC Digest <ihc-digest@domain.elided>

>
> A number of our guys pointed out to me that the oil bath does not do as
good
> a job as a good paper filter. Gave me actual test data, among other
things.
> The oil bath relies on the dust "falling out of the air" and into the oil
> for its filtration. If the dust doesn't fall out, then it goes down into
the
> carb.


**************
Jim In Mesa - James Lidberg
jameslidberg@domain.elided
'79 Scout II/4X4/345/Edelbrock 1400/727/D20/3.07 open/PS/PB/4"Trailmaster
Copyright 2004 All rights reserved