For those of you maintaining older diesel locomotives, your familiar that most have a standard H-filter arrangement for filtering water and dirt out of the control air system. Has anyone made any attempt to replace the H-filter arrangement with a more modern 824 filter? My reasons for bringing this up is, I'm wondering how much longer venders will be carrying the H-filter element before it gets discontinued. Also, the H-filter only has a manual blow down whereas the 824 filter is equipped with an automatic drain valve -- a nice feature to have. Has anyone made any attempt to equip an H-filter with an automatic drain valve?While a one-for-one swap of the two devices sounds easy enough, the 824 filter is a bit larger than the H-filter, and hence trying to shoe-horn it into the air brake rack of an RS-3 would definitely be a challenge.

I believe that this is indeed possible. Untill recently there was an old FM switcher still in revenue service not far from me, and I was given a guided tour. They had the same problem, and what they did was to replace some of the old air lines (which needed it anyway, too much longer and some problems would have shown themselves) with new ones that where longer and thus put the new filter in a different location. It worked surpisingly well.Sadly this loco has in the past year been taken out of service, but on the bright side it has a new paint job (same scheme, just fresher paint) and is now running in a museum.

The actual function of the H filter is to condition the air before it enters the brake system, e.g., either a 6 or 24 system.The way most RS-3's are piped, the air that supplies auxiliaries such as horn ,bell, control air, etc, is tapped off the system before passing through any sort of filter. So, in effect, this air is subject to minimum-if no conditioning.The other thing to recall about an RS-3 is the combination of the air compressor location and the crude filters on the compressor intakes will tend to take any fluid under suspension within the confines of the hood and entrain it within the compressed air stream. So, perhaps the place to start is to update/upgrade the compressor filters. My thought on cleaning up the control air feed is this: The best course of action is to survey one of the industrial supply outfits and select a suitable coalescer/water trap that can be piped into the control air feed without disrupting the original piping. One less railroad specialty item to be dealt with during periodic maintenance. The replacement of an H filter with an 824 seems like an awful waste of money-as one doesn't get any additional 'performance' out of brake equipment such as 6 or 24. However, if one was to convert a locomotive to 26, the substitution of an 824 might buy one some additional reliability-as many of the rubber parts found in 26 equipment don't really care for water/oil.As for elements for the H filter, I kind of suspect that a trip down to NAPA will yield something that is pretty darn close in size. Dave