Inertial Filters?

Hey guys - so what exactly are these "Inertial Filters" anyway? I always assumed they were just like the air filters on a car - filtering the air intake for the engine. Then I got to thinking (always a problem) about the work "inertial" - what's the differance between inertial and non-inertial filters. What locos have non-inertial filters? What are they called "inertial"?

 

They are used where there is a good possibility that sand and small pebbles, twigs, etc. might get drawn into an air stream and have enough mass and velocity to puncture a filter element. They spin the air stream, so centrifugal force will direct heavier particals out away from the filtering elements, (usually cloth or pleated paper), so these can take care of dust and finer particulate matter. These were used in high volumn installations. I'm not sure they are used on trains, although I believe some were tried some time back.

 

From Watash's description they appear to be the same as a "Cyclone Separator" much used in the chemical, petrochemical and steel industries to remove solid particles from gas streams.
Best wishes,
John

 

I think the UP gas turbines (Big Blows) used something like this for first stage filtering of turbine intake air. I don't remember what GE or UP called these filters.

 

I do not know exactly how they work, but I do know that "inertial filters" are used on all locomotives with a pressurized engine compartment. Most modern Diesels, starting with the U25B, have an engine compartment that has a slightly higher pressure than the surrounding air to keep dust and grit out.

 

<blockquote>quote:</font><hr>Originally posted by watash:
[QB]They spin the air stream, so centrifugal force will direct heavier particals out away from the filtering elements <snip> I'm not sure they are used on trains, although I believe some were tried some time back. /QB]<hr></blockquote>

Thanks - To answer your question watash - most modern diesels have inertial filters - at least that's what the detail part manufactures call the parts us modelers apply to the shell. I am trying to understand more about how the engine designs work.

Better modeling through understanding!

 

I'm not too much up on deezulz. I think I remember it is hard to get coal into that little bitty hole for fuel, and they are miserable steamers!

Gregg just reminded me of one thing, I think the pressurized engine compartment was also to remove fumes as well as dust etc. Maybe?

[ 05 August 2001: Message edited by: watash ]</p>

 

Not up on locomotives, but I recall that jet engines have a 'filter' which is just a wider sopt by the turbine blades. Solid bits (known as foreign object damage, or fod), being heavier than the air, are centripetally flung out to the sides and discarded, while the air goes through unmolested.
Again, I'm no locomotive expert, but this'd be my guess. Is the filter disk-shaped, reasonably wide but probably not very thick?

 

<blockquote>quote:</font><hr>Originally posted by watash:
and they are miserable steamers!
<hr></blockquote>

Have you seen some of the old Alco diesels at work? Used to be called Honorary Steam Locomotives.

[ 05 August 2001: Message edited by: yankinoz ]</p>

 

<blockquote>quote:</font><hr>Originally posted by Biggerhammer:
Is the filter disk-shaped, reasonably wide but probably not very thick?<hr></blockquote>

I only know what they look like on the outside. Big square boxes with big square air filters on the side. They could be round on the inside. They seem to take the full width of the engine. They are big - or at least look like they are big.

 

Check out the description and photo by the filter manufacturer (Camfil-Farr) here:


http://www.camfilfarr.com/trans/products.htm#inertial


My interpretation is that moving air drawn in by the locomotive while it is traveling down the tracks is moved through the filtration system.

Anyone else have better information?

eNjoy


Don B

 

Let me try and explain the inertial filters as used on EMD hood locomotives. These are the primary air filters for engine intake air. There is a filter on each side of the long hood above the generator compartment (section closest to the cab). Intake air is drawn through these filters through tapered openings (see the diagram). As the air reaches the back of the filter it is forced to change direction before entering the generator compartment. As the air quickly changes direction, much of the dirt, dust and foreign objects drop to the bottom of the filter. An inertial blower motor (mounted on top of the locomotive between the two filters) is connected to each filter and sucks the largest dirt particles and foreign objects out of the bottom of the filters and dispells them through a grille in the top of the locomotive. The cleaned air in the generator compartment is then drawn through a secondary set of filters before entering either the turbo or blowers and then the engine itself.




Chris Toth

 

cool! Thanks Chris.

Is the blower you speak of in the 'blower housing' on the fireman's side?

Where is that scan from?

 

Rob:

<blockquote>quote:</font><hr>Is the blower you speak of in the 'blower housing' on the fireman's side?<hr></blockquote>

No, the inertial blower motor is mounted under the inertial hatch on top of the locomotive. Remove that hatch and the blower is attached to it. It fits in between the two filters (see the diagram above and look for the arrow pointing up).

The blower bulge on the side of the EMD units covers two things. The auxiliary generator drives two blowers--one to cool the main generator and the other to provide cooling air to the traction motors. There is also a fuel breather pipe that extends up from the fuel tank and loops back down (This pipe was external on most SD-7 and SD-9 units).

<blockquote>quote:</font><hr>Where is that scan from?<hr></blockquote>

From one of my many EMD manuals.


Chris Toth